2003-2007 Cummins No Start? No Problem!

Diesel Fuel Economy / MPG, Diesel Truck Maintenance, Dodge Cummins, Ram, Tips and Tricks, UncategorizedTags , , , ,

We get a lot of calls on a daily basis with customers trying to diagnose some type of issue with their truck. Fortunately, we’re typically able to help diagnose and give recommendations for products or procedures to remedy the issue. We must have developed quite a name for ourselves over the years, as frequently we even get calls from shops that are scratching their heads, hoping we have the golden ticket, and fortunately, we usually do! One of the most common calls we get are from customers with a 2003-2007 Cummins that have developed either a hard start or no start condition. In order to help out, we had our very own Tyler Lucas, put together this step by step tutorial that you will hopefully find insightful. Tyler has been elbow deep in diesel engines for years, especially Cummins, so he is a wealth of information when trying to cure a plagued engine.

The very first thing that needs to be checked is battery voltage. When I say battery voltage, I am not talking about just getting a voltmeter and putting it on the positive and negative posts, as you will only get what’s called a surface charge, which won’t tell you what’s actually going on when the battery is under load (i.e. cranking). It is very common to have a battery read around twelve volts on a surface charge, but then drop well below nine (the minimum voltage to allow for cranking on 2003 to current Cummins) when under load. Overall, make sure that when you test the battery, you are doing so under load by cranking the engine and watching the voltmeter.

Let’s now say your batteries are good. You then ask yourself, “Tyler, what now?” Don’t worry sad no start truck, we’ve got your back! Let’s now dive into the fuel system. First off, let’s get this out of the way, Ram trucks NEVER had the best luck with lift pumps. A lack of lift pump flow will not only cause a no start issue, but depending on how it failed, can cause other issues that we will discuss further into this post. The factory lift pumps on the 2003-2007 Cummins produce a dismal 10-11.5 PSI at idle. But unfortunately, due to these pumps’ inability to actually produce volume, the pressure drops off considerably as load increases. And remember, while pressure is definitely an important factor as this is the rate at which fuel is dispensed, volume is equally, if not more important, as it’s the amount of fuel. This drop in pressure is even greater when fueling modifications and upgrades are added, such as programmers, upgraded larger displacement injectors, and higher volume injection pumps, because guess what, they are all demanding additional fueling for increased performance. When you start going below 5 PSI, you are not supplying the injection pump with enough fuel to properly drive the injectors, and at the very least, you will experience a loss of power and fuel economy. Some customers will notice the truck “falling on its face” or flat lining with power as the pump simply cannot supply any more fuel. After time, the pump will just stop working due to being over stressed and constantly running at maximum output. And this is exactly what we will be testing for next, the health of the lift pump. The best way to check your fuel pressure is to install an inline pressure gauge before the injection pump. But we understand that in many instances when your truck won’t start, you simply don’t have the time or resources to collect the parts and tools to accomplish this. So we have an alternative method for you by checking the general volume output of the pump. In order to do this, remove the fuel supply line before it connects to the injection pump and place the open end into a bucket under the truck. Next, hop in your truck, and “bump” the key. When I say bump the key, just turn the key to crank the engine for a second in order to engage the pump. At this point, you should hear the pump run the duration of its cycle. For reference, the 2003-2004.5 trucks came equipped with a block mounted lift pump and the 2005-2007 trucks came from the factory with an in-tank lift pump, yet many of the 2003-2004.5 trucks were later retrofitted with this same in-tank design. This will give you a gauge on where to listen for the “hum” of the electric motor on the pump. Once you’ve bumped the key, presuming the pump is operating normally, you should see fuel dumping into the bucket. However, if no fuel comes out, then it’s safe to assume that this is the culprit of your no start issue. In order to correct, you’ll need to replace the lift pump, and no better time to upgrade than now. Our preferred brands of aftermarket lift pumps are FASS and AirDog, simply because they have options for stock to fully modified engines, offer filtration that is far superior to stock for increased protection, and come standard with a lifetime warranty.  Out of those manufacturers, our most popular models are without a doubt the FASS Titanium and AirDog II-4G. For most trucks, even slightly modified, a volume of 95 or 100GPH is ample to properly supply the injection pump for a lifetime of trouble free service. And just remember, bigger isn’t always better in terms of lift pump choice.

But Tyler, I checked that and everyone knows that Dodge lift pumps are sub-par at best. Stay with me here, we are graduating to the high pressure side of the fuel system now. One of the most common problems I see on common rail Cummins, is the pressure relief valve, or PRV for short. For those unsure of exactly what I am talking about, this is the large fitting on top of the fuel rail that has a fuel line attached to the top of it via a banjo bolt that then returns fuel back to the factory fuel filter. The pressure relief valve is designed to do just as the name implies, relieve pressure. Specifically, it begins to open at 26,000-27,000 PSI and return any excess fuel to be recycled back into the system. Commonly, these valves will get stuck in the open position and stay that way when the truck is turned off. If the valve is stuck in the open position, the truck is unable to build the necessary fuel rail pressure (5,000-7,000 PSI) for startup. Remember, this is a common rail system and that pressure is absolutely necessary for the fuel to be atomized properly to create combustion. To visualize this, imagine trying to blow up a balloon with a gaping hole in the side of it, not happening, right? In most cases, we sell either a new replacement pressure relief valve to return the system to stock, or a PRV Block Off to eliminate the relief valve all together.; Some would argue that installing a block off is unwise when combined with a factory fuel system because it cannot protect itself against pressure spikes. Now, I have been around these engines quite a bit, and have installed countless block offs in completely stock trucks without a single issue. This fuel system is designed to handle exceptionally high pressure, so a small spike in pressure for .00001 of a second should not cause any damage. The benefit of installing a block off as opposed to a new PRV? Well, that’s simple; number one you’ll never have to worry about a blown PRV again, and secondly, a block off is substantially less money. With that said, I don’t recommend running a stock fuel system with a rail pressure box, such as the TS-MP8 on its max setting, combined with a block off, as it will over stress the fuel system. Which one is right for you? That’s up to you and your truck, but as always, if you need guidance, feel free to contact us and we will help steer you in the right direction.

Before we go to another portion of the fuel system, another quick check is the transfer or connector tubes. This is the part that transfers fuel from the high pressure common rail to the injectors. The fuel line from the rail connects to the inlet and is seated against the injector via a jam nut. There was actually a TSB (Technical Service Bulletin) from Dodge years ago regarding the tubes losing torque, causing them to leak between the injector and the tube. This can easily be checked by removing each individual fuel line and checking the jam nut to ensure it has the proper torque. I torque tubes to around 55 ft. lbs., factory spec is 35 ft. lbs.

Now you may say, “guess what Tyler, I’ve already checked that, what’s next on the docket?” Well fellow Cummins connoisseur, I have your back yet again. This next test gets a little more involved. Each of the six injectors in your engine will return fuel. The maximum amount of leakage on a warm engine is 160 mL per minute at about 1200 RPM’s. During cranking, you want to see 90mL, or about the amount of fuel that would fit in a double shot glass, essentially not a lot of fuel. In order to perform this test, you will need that trusty bucket yet again to capture the return fuel, as well as a small section of hose that will be used to extend the return line somewhere where you can watch and hold the bucket. If you look in the driver’s side front fender well, there are two hard plastic fuel lines with a clip attaching them about halfway up the engine. One is a return from the CP3 injection pump coming out of the fuel filter canister, and the other is for the injectors coming from the back of the head. Make sure you are only dealing with the line coming from the back of the head. You will take that line and detach it by releasing the clip. Now that the return line is free, attach your hose to extend into your trusty bucket. Finally, have a helper hop in the truck and start cranking. Unfortunately, this particular test requires you to crank the engine for an entire minute, which will seem like an eternity to you, your starter, and your batteries. Being the spec is only 90mL, if you have gone past that in the first 15 seconds, just stop, as we know there is a problem at that point. Usually a good working set of injectors that are returning the proper amount of fuel will just lightly trickle out of the return line. Any result over 90mL means the injectors are returning excessive fuel, and they either need to be repaired or replaced. This is also a great test if you have lost fuel economy, but the truck seems to be running properly. A slight drop in injection pressure caused by excessive return will cause improper atomization, therefore decreasing efficiency. That’s another topic I’m sure I could elaborate on for a few pages about, but that’s for another day!

If you have checked everything and we still have a no start condition, I would look at the CP3 injection pump. The only way to really test the output of the CP3 is to send it to a fuel shop and get it on a test stand. There is one test you can do at home, but it is definitely a backyard mechanic test, and not a true determinant for the health of the pump. We will be looking at the Fuel Control Actuator, also known as the FCA, M PROM, and I have even had people call it a pressure regulator. This is the two wire actuator coming off the back of the CP3, and is the only electronic connection on the pump. This sensor basically tells the CP3 what pressure it needs to be at. In some instances, this actuator will either get stuck in a certain position or stop operating altogether. When this sensor is unplugged, the pump loses its ability to restrict flow, thus will run at maximum pressure, which is exactly how we will run this test! We are going to unplug the FCA and attempt to start the truck. Keep in mind you Cummins techs out there that say this is not a valid test, as this test is not for you. This test is for the hard working Average Joe that doesn’t want to take his truck to you and pay your $120 per hour labor rate. Alright, now back to the test, if the sensor is unplugged and the truck starts, we can assume the sensor is not functioning properly, which again, is a very commonly failed component. Now very important, if the truck starts, make sure you quickly turn it off, as with the FCA unplugged, there is no metering of the CP3, which means it will run at maximum capacity, causing elevated RPM’s and a rough idle.

All of the above tests are intended for the do-it-yourselfer, and will typically lead to the underlying cause of the issue in most instances we have encountered. However, if after performing these tests the diagnosis is still uncertain, the problem is probably more in-depth. As always, if you have any questions about the above information or any of the products mentioned, do not hesitate to give us a call or send an e-mail to [email protected] and we would be happy to assist.

Tyler Lucas
Assistant Sales Manager

[email protected]

(888) 99-DIESEL Ext. 103

263 thoughts on “2003-2007 Cummins No Start? No Problem!

  1. What do I do when I still have no fuel out the high side of the CP3 Ive taken the line off and there is no fuel while cranking. I am getting slight pressure out the return fitting when I crack it open. With the lift pump running.

    Any advice would be great.
    Thanks Sam

    1. With all the lines connected, if you unplug the FCA, will the truck fire? Unplugging the FCA should make that pump go to max pressure. You may have an issue with the pump itself.

  2. Nice write up Diesel Josh. The one thing that I would add as I have been faced with this is when you have a condition where the cranking RPM falls below the threshold of what I believe to be 150 RPM, (measured with a scanner) assuming CP3 Pump works fine and injectors do not leak over the threshold (either via the connector tubes which is measurable via the return or the injector tips). If one is not able to start the truck due to lower than 150 RPM which I believe to be the minimum cranking RPM, however when plugged in the engine is easier to turn and the RPM goes over 150 and the engine starts then one can rule out the fuel delivery, including injectors, CP3, lift pump etc. This is where one wants to suspect the electrical delivery such as the week batteries or starter and wires. It does not meant that fuel delivery is optimal as the additional cranking speed may be required to bump up the rail pressure to the minimum requirement however this would only be seen in borderline situations. All I know is if a truck starter can’t produce 150 RPM then that’s the first thing to fix before looking at fuel delivery.
    Thank you for taking the time to do such a great write up.

    1. Thanks so much for the response on the write up. And yes, you are exactly correct that you at least need to have adequate charging and cranking speed in order to initially fire the engine. Great response and additional information, thanks again.

  3. Hi, thanks for the very informative article.????
    But just to be sure, if my truck starts fine after being plugged in for three or four hours than that rules out fuel delivery as a possible cause?
    I’ve replaced one of my grid heater solonoids and checked the other one and it works. I’ve also cleaned all of my connections and the grid heater seems to test fine and heats up to some extent (not sure how hot it’s supposed to get) but my truck is still hard to start at temps under 70f unless I plug it in.
    Any suggestions would be appreciated. ????

  4. So I cap the #3 injector at the rail and it will start. I reconnect the injector line and it will start. If I do not cap it off and leave the injector line alone it will not start no matter how long you crank. I put on new injector line. Same issue. Makes no sense to me..

  5. Well if you cap # 3 and it starts, and when fuel is allowed to flow to that #3 Injector it doesn’t, its more than likely returning to much fuel to where it is dropping rail pressure enough to not fire the engine. I would move #3 injector to another hole and see if the problem moves to that hole. If it does then you know you have a bad injector.

  6. nice write up, have done everything in your article still no start, have a 09 6.7 with low km truck just quit on the hwy. new lift pump new injector pump new crank sensor. will crank all day lots of amps. no codes on the dash ( engine light will flash, have a lift pump gauge not working no other codes) I have a delete kit that was installed yrs ago no issues. After trying everything no luck now I know what your going to say but I tried a sm squirt of either engine fired right up but would only run when throttle was 1/2 or greater will stall when i let it try to idle. Is there a sensor somewhere that controls the fuel on start up? Any help would be appreciated .

  7. I have a 2007 dodge Cummins 6.7 6speed..terminals went bad but would still push start easily..changing out terminals a wrench arched the grid heaters solenoid and has not fired up sense..any ideas would be greatly appreciateed

  8. the truck will run until it gets a half tank of fuel . the truck will start back up but want go far before shutting down again. put fuel in truck will run ,until half tank again and runs good

  9. My 04 will only start on either or roll start. New crank sensor. I checked for fuel getting to the fuel filter and I can hear the pump. Does the grid heater have to heat up for the cummins to start?

    1. Negative. Only in cold climates will it make it noticeable easier to start with the grid heater, but it will typically not prevent it from starting unless its VERY cold, which is not typical for this time of year, of course. Further, I’m not following, are you saying that it only starts on a roll start, as in bump starting like you’ve got a manual transmission, get the truck rolling and pop the clutch?

  10. Great article a lot helpful information. Found that the truck I was working on had four loose injector nuts. Tighten them all and the truck starts and runs great.
    Thanks for the help I will definitely be going to diesel power products for any future parts or advice. Thanks

  11. My 04 has an intermittent stalling problem. I can drive it for a few hours and it’ll run great then will sometimes stall. Engine will crank but won’t start. If i let it sit a few minutes it will start but then die. This will happen 3 – 4 times then will stay running and could be fine for hours. I replaced the lift pump thinking it was the culprit. I do not hear the lift pump run when the no start condition occurs. My question is what controls the lift pump and supplies power?

    1. It definitely sounds as though its a fuel pump related issue. Your ECM controls the lift pump operation depending on key position, which goes through a fuel pump relay. Presuming the lift pump is good, since you just replaced it (again, making a presumption) look through all of your wiring and fuel pump relay to ensure there is no break or corrosion. Beyond that, I would recommend checking the power to the pump when you have these issues. If there is power going to the pump when it will not start, its of course a bad pump again. If there is not power, you’ll need to work your way back to see where its losing power. In some cases, it can be a faulty ECM not triggering / turning on the power to the pump. Further, as a side note, 2004 models originally had the lift pump located in the engine bay. Later, it was determined this was a bad location, causing them to be susceptible to failure. Dodge released a retrofit kit that would move the pump into the fuel tank’s pickup basket assembly. Not sure where yours is located.

        1. You are correct, I misspoke. After some research again, I was thinking of when the in-tank conversion is done, then a relay is added. From what I can recall and after confirming with some quick research, there is no relay for the stock filter mounted lift pump. When the in-tank conversion is done, an in-line relay is added, but in your case, its completely controlled by the ECM. In the instances when your truck will not start, confirm if you can hear the lift pump cycling by turning the key to the on position and listening in the engine bay. If nothing, then its confirmed you’re either not getting power to the pump or the pump is bad. The stock pumps are known to work intermittently when they are failing, so unfortunately it may be that its going out again. I would recommend giving us a call and we can help steer you in a direction to get the truck back up and running reliably again. 888-99-DIESEL.

          1. I will definitely call. Now I can get it to act up. I can drive it for about 2-3 miles then shut it off. Let it sit for about 5-10 minutes then it will continuously start and die. If it sits for about 15 minutes i can usually get it to start and drive. I’ll call soon. Thanks for the help!!!

          2. That does sound like the lift pump is overheating and not allowing it to start if you try and start it when the pump is still “hot.” I had to read your symptoms several times, as it almost sounded like a different issue. In instances when it will start back up again immediately, but not as likely the longer it sits, that, in many cases, is actually the pressure relief valve on the fuel rail that is failing. But again, you are the opposite situation. We look forward to hearing from you.

  12. My lift pump is located on the side of the filter housing. Thanks for the input and I will post my findings! I wish it would quit for good so I could track it down.
    So does the fuel pump retrofit eliminate the hoising mounted lift pump?

    1. Yes, the dealer retrofit kit will eliminate the filter housing mounted lift pump with a new unit that mounts into the fuel tank’s “basket” assembly. This will include a new wiring harness, as well. While this is a good upgrade over the stock filter canister mounted unit, I would recommend upgrading to a FASS or AirDog unit for better reliability and filtration over the stock units. Otherwise, you could always go with FASS’ DRP that is merely a substantially better lift pump than stock, but keeps it in the engine bay. This is better than the retrofit kit, but not as good as a traditional FASS that mounts to the frame rail. Overall, its a good way to get a much better pump with an easier installation and less expensive than a frame mounted unit.

  13. Tighten the jam nuts at the end of the injector lines may have solved my issue. I have a very short crank time now(comparatively) after completing this. Thank you!

  14. Hi. Found your write up to be very helpful but am still needing expert advice.
    Here goes. Filled up the truck with diesel 5.9, drove 20 miles and truck died conveniently in front of son in laws work. Got out of truck to notice fuel spilling all over the road. Son popped hood and said it looks like it’s coming from fuel rail. Replaced the lines but now it won’t start. Cranks but won’t turn over. Lift pump works, got fuel in filter but only about 1500 ps. Neighbor put it on a computer and said it’s either cp3 or fuel injectors. Now before I start spending big dollars on injectors and or pump is there a way to test the pressure relief valve short of ordering a replacement?

    1. Hi there, thank you for reaching out. With the truck not running, remove the fuel line on the top of the pressure relief valve and physically move it out of the way. That line routes relieved fuel from the valve back to the fuel filter canister. Fuel will take the path of least resistance and without physically moving the line off of the top of the valve, fuel coming out of the line will make it look as if it is coming out of the valve. Once the line is removed, crank the truck. There should be no fuel coming out of the top of the valve during cranking. If there is fuel coming out of the valve, it is bad and needs to be replaced. I would do the injector return test that is outlined in the 3rd to the last paragraph in that write up. If you have any other questions, feel free to give us a call at 888-99-DIESEL, as well.

      1. So, checked pressure valve. No problem there. Did the injector test and had lots of fuel with in a second. So that tells me it’s an injector. My question now is, suppose it’s only one injector gone bad can I get away with purchasing just one or do you recommend the whole set?

        1. We get this question a lot. Yes, if you only have one injector that is returning higher than normal, you can definitely replace only that one injector. BUT, in our experience, when doing this, its typically not long before other / all other injectors begin to fail, meaning you’re in there again replacing more injectors. Obviously, its best to replace all of the injectors at once, and if the truck has in excess of 150,000 miles with the original injectors, the rest are probably on their way out, as well.

  15. 2005, stock, 5.9, 100,085 miles, auto. 90 degrees, humid and sunny. After a 70 mile interstate trip and 4 hours shutdown, with less than 1/2 tank of fuel remaining (fuel at least a month + old) at the first stop sign 1 mile away on the return trip, truck hesitated upon applying throttle to proceed but moved on without issue. Ran fine to next stop sign 2-3 miles away. Next 5 stop signs, 2 miles apart, engine stopped in mid-intersection of each upon throttle application. 15 seconds of cranking each time, restarted, idled smoothly, and ran to next intersection where it died again. On to highway speed at 55 mph, 3 miles and truck died completely. Coasted into parking lot, and gave up trying to proceed further for night. Returned with a used FCA temporarily removed from a twin good running truck of same vintage as above. Started after long cranking, stalled a couple of times but began running smoothly. Tried to proceed, but 8 miles up the highway, truck died again while at speed as if out of fuel. Towed to a diesel shop, and waiting diagnosis next week. Ideas from here for now?

    1. Thanks for reaching out to us and sorry to hear about the issues with your truck. In regards to the P0088 code you’re getting for higher than desired rail pressure, you were correct in replacing the FCA as that is many times the cause, however, since it did not alleviate your issue, the next step would be to check the rail pressure sensor. Otherwise, we’ve seen that code thrown when its not necessarily the excessive rail pressure causing the issue, just the fact that the truck had higher than desired rail pressure during the “issue” because your RPM’s were lower because of the misfire resulting from the rough running condition, as an example. So again, its not that the high rail pressure caused the problem, its that the rail pressure was higher while the engine was running rough and even dying, than under normal circumstances. Its almost sounding like a fuel quality issue or even lift pump related. I’m sure the shop’s first order of business will be to check your fuel filter which will tell the tale of fuel quality after initial inspection. From there, presuming they will check the health of the lift pump and move on from there. Good luck in getting the truck back up and running.

  16. I have performed all these test but truck would not start without starting fluid. It would not start without the fca unplugged but once it started I unplugged it and idle did get rough. Is that normal? I have replaced both pumps. Once running it has all power it needs and get a speeding ticket if not careful. Any help would be nice.

    1. Yes, it is definitely normal for the truck to run rough once you unplug the FCA as the rail pressure will run higher than desired at the lower RPM’s at idle. If you haven’t already, another thing to check would be the rail pressure sensor as its sounding like possibly the ECM is not properly registering the amount of rail pressure until the truck is running. The simplest method would be to swap the sensor from another truck if possible.

  17. Ok thanks. I did notice today when I tried to start after sitting for 24 hours the rpms only got to 100 and once ether kicked in it fired when it reached 200. It seems I may have 2-3 issues that may be going on. I will post what I find out. It may take a few days but I will post an update. Thanks again.

  18. Have 2006 5.9 that is very hard starting when warm,starts fine when cold . Have changed both pumps ,and filter . My question is which sensor should I start with ? It was checked for codes at the dealer and nothing came up ..Help please ..

    1. Hi there, and thanks for the question. The first thing we would recommend checking is your pressure relief valve located on top of the fuel rail, which there is a tutorial on how to do in this blog post. If the PRV checks out fine, then the next step would be to test the fuel return rate of the injectors. Good luck, and let us know if you’ve got any other questions.

  19. I have an 07 5.9 that developed a long crank problem. it started cranking for 2 times as long as normal a few weeks back. Since then it has gotten long up to 15 seconds and sometimes an initial of 15 followed by 10. It is assumed that it’s taking this time to build up rail pressure. Once it starts it runs like a champ and has no issues running, pulling for hours or hundreds of miles, unless i kill it. This issue doesn’t change if it’s cold or hot, warmed up for first start in 3 days. As soon as the key is turned off and you quickly try to re crank it or let it sit for days its the same. I have put a plug in the place of the rail pressure relief valve and just finished ordering a rail pressure sensor. What are your thoughts on this one? Thanks in advance.

    1. This sounds exactly like injectors that are returning too much fuel. I would check the fuel injector return rates while the truck is cranking. This can be done by removing the return line at the rear of the head and plumbing it into a bucket that can collect the return flow. During cranking, there should be a very minimal amount of fuel coming out of the line, as in drops of fuel, and definitely should not be a steady stream. If it is a steady stream or anything other than drips, we have injectors returning too much fuel and it is just taking excessive cranking to overcome the return and build up enough rail pressure to start the truck. Presuming so, the trucks fuel mileage is probably down, as well. Hope this help alleviate your issue. If in fact you are experiencing excessive return, the fix would be to replace the injectors and injector connector tubes. We have numerous options available and if you have any other questions, please do not hesitate to give us a call at (888) 99-DIESEL, send an e-mail to [email protected], or reply to this message, as well.

  20. I have a 2005 just installed new injectors, wouldn’t fire. Deleted the relief and fired right up. Went for a little rip and it ran ok had code MAF that was unplugged. Went over the truck and got it buttoned up, had it idling for about 15 min. Went around the block and down the street it died and won’t fire at all now.

    1. Did you completely clear the MAF code? You can leave the battery cables completely unhooked for about half an hour if you don’t have a scan tool to accomplish this. If you’ve done this, its possible you have a bad injector harness. Short of completely replacing, you can test it by disconnecting each wire from each injector and ohm testing the harness. You should get 0.05 ohms or less. If you have a pinched wire, it could easily be causing a hard or no start issue. Another thing to try, unplug the Fuel Control Actuator (FCA) on the CP3 injection pump and try to fire the truck. The FCA is a metering device, so if it fires up, immediately turn off the truck as it will overpressurize the system. But if it does start, chances are you need a new FCA.

      1. Yes I cleared the code with my smarty. I tried unplugging the FCA and no change. I redid my injectors and injector tubes just to be sure, tried again and I got inlet air temp p0073, cp3 pump p0251, cooling fan p0480. Still no start. Thanks for the help so far.

        1. Okay, first off the fan clutch code p0480. That could be a blown fuse or a bad fan clutch itself. While not something that “notoriously” fails, they can and do fail. The P0251 code, that seems associated with unplugging the FCA (fuel control actuator) and should clear and we would expect that not to return once cleared. The air inlet temp code could be related, but that is not stopping the truck from starting. I would suggest at this point, starting somewhat from the beginning and verify lift pump pressure first. Something is being missed here, you have to be losing pressure somewhere. For it to die randomly, the truck is either not getting fuel to the injectors or its electrical like the injector wiring harness. If you’re able to test what the fuel return volume of the injectors are for 10 seconds of cranking and what is the actual lift pump pressure, that would help in diagnosing the issue. Also what is the resistance reading on each injector solenoid and harness.

          1. Ok so the injectors test out between 0.4 and 0.7 ohms and the harness tests at 0.1 ohms with a fluke meter. I think the fan code comes from a broken pin in the connector. I did a quick fuel return test and it looked a bit more then it should so I redid the injector install and double checked the torque specs. I cleaned out and dielectric greased connectors. I have not tried to fire since I did this. I have a 150 fass with new filters and the cp3 has a bag of parts kit. I don’t have an actual pressure reading yet but I am working on that. I will do a better return test and get back to you.
            Once again thank you very much.

          2. So it sounds as though the harness is good. Let us know once you get a new return test done as the preliminary test sounds as though it may be causing excessive return. But even at that, it would have to be very excessive to cause a no start issue. Possibly, you had an issue with how the connector tubes were seating into the injectors, as this is a common issue, and hopefully your re-installation cures this issue, if it was the culprit. Long story short, most people install the injector completely, then screw the connector tube in, when in fact, you need to slightly tighten the injector, then the tube, then the injector a little more, etc. so the tube can properly seat into the dimple on the side of the injector. Otherwise, fuel will bypass the injector, or even partially block it. Good luck!

          3. Ok so just did a return test and I’m only getting about 10 – 15ml of fuel. I hand tightened the injectors and backed them off and installed the tubes and torqued to 50 ft lbs I know that more then suggested but I want to make sure they are seated. Could my cp3 be acting up? This is my hot street project and everything but injectors sat on my bench for over a year.

          4. The return sounds good and your reinstall with the injectors and tubes is spot on. Honestly, they can use more torque than the recommended to really seat them well. Yes, starting to lean towards CP3. Did you just install the bag of parts, or had it been on the truck for a while? Have you tried swapping out the FCA with the stock one? Also, when you change out the fittings on the CP3 with the BOP, did you absolutely make sure that the little tiny ball was reinstalled? Its easy to miss.

          5. I did the bag of parts a couple years ago. Was one of my first mods. I actually did drop the check ball in the driveway and had to order a new one. I just swapped the stock FCA in and no change at all. I’m honestly at a loss. I just need to move the dang thing so the fiancé can park in the garage now that the snow is flying. I defiantly need to get a rail pressure gauge. Any real way to see if the cp3 is done?

  21. I have a 2006 2500 and it wont even crank over it just clicks so i pulled the starter put a new one in and it still just clicks i used a test light cheched the wire comming from the ignition and thats good the clicking is comming from a relay by the drivers side battery where do i go from here?

    1. From the information you’ve given, this honestly sounds like you simply don’t have enough battery voltage at cranking. Your ECM requires a minimum of nine volts to do absolutely anything. What we would recommend doing first is to check the battery as you’re attempting to crank over the engine, so have one person holding a voltmeter on the battery post watching the voltage drop and another turning the key. Even though you may be showing 11+ volts at static level, you could very easily be dropping below nine when trying to crank, which would cause the relay to merely click.

  22. I have an 07 Dodge 2500 with the 6.7 cummins and as above I am unable to start it after getting water in the fuel. So far I’ve dropped the tank, cleaned it and installed a new pump and installed a new filter. It was still showing low fuel rail pressure and gave me the error that the rail pressure relief had gone off so changed that and still wouldn’t start so changed the injector pump and had the injectors cleaned. It still won’t start but will try with a shot of either can jou give me any suggestions as to what else it could be?

    1. I would be looking at injector return flow. Just simply cleaning injectors will not fix them. Water contamination creates cavitation under the high pressure that the fuel system is under. It will do just as much damage as sediment would. I would test the injector return rate for sure. The maximum allowable return while cranking is 90 ml per minute. So not much that’s only just over 3 ounces.

  23. Great write up and thanks for giving out the information. It seems everywhere else you look for some help, someone wants to make money for helping others. I’m about to start the tests. Before I do, the not start problem I’m having is when we drive our 2007 dodge ram and park it and try to re-start it again in about 2-5 minutes later. Just cranks. I’ve noticed if you wait longer it takes a bit longer to crank and finally fires. If you at least wait somewhere after about 15-25 minutes later it starts fine. So if you take it out for a long trip and get back in it to start right away not a chance. let it sit for a while and it starts. We already have a new pump in the tank from the summer. If it were the pressure relief valve? Wouldn’t the pressure sensor set an engine code and light up telling not enough rail pressure? If so I’m going to the next step. if not then start with the valve and next in order. Thanks.

    1. The pressure relief valve is a great place to start since you have already addressed the lift pump. When it is in its no start condition I would remove the Banjo bolt on the top of the relief valve and push the line out of the way. See if it is relieving fuel when you are cranking the truck. If it is perking fuel when cranking, the relief valve is bad. Sometimes they will throw a code and sometimes they won’t. I see this issue a lot with trucks that have high return rates on the injectors, so the injector return flow test would be the next test if the relief valve checks out good. Good luck and let us know if you have any other questions.

  24. If I have to much return fuel from back of head should I try injector tubes first or am I wasting my time and just putting off the inevitable.

    1. Unfortunately, its not common to have the connector tubes be the culprit for a high return rate unless you’ve had them out for any reason and they aren’t properly seated into the injector. In that particular case, unless they were just loose, you would have an issue where the tip of the tube has a seating ring around it from where it should be seating into the injector body, but not properly seating. But again, that only happens typically after you’ve had the injectors and tubes out. Further, its POSSIBLE for it to be the Fuel Control Actuator (FCA) of the CP3 injection pump, but in most cases, these don’t supply enough pressure, but your symptom would be caused by too much pressure. So yeah, you’re most likely needing new injectors. Let us know if you have any other questions.

  25. With a longer start cranking and driving at 55 above no pedal repsonse (power nothing) and p0148, but drives, idles fine indicate or isolate problem better? If try describe better, engine taking extra time cranking to fire off, then when driving acceleration fine for few miles, when want power to go faster or load on engine past 55 there no power response, push pedal floor with nothing. Left off can continue driving no problems. Like dang governor on engine. Would these sequence of failed items be similar? Much thanks any insight/help.

    1. These symptoms and the code you’re getting could be a handful of things because essentially that code is saying that the commanded (or desired) fuel pressure it not meeting the actual. Our recommendation would be to start at the beginning of the fuel system and work your way forwards. The big tickets items to check would be number one, lift pump pressure, both at idle, as well as at cruise. Next, check the pressure relief valve as it could be bleeding off prematurely. Third, have the return rate of the injectors tested. These three would be the most likely culprits, but it could also be the fuel control actuator (FCA) on the CP3 injection pump, fuel rail pressure sensor, or even an issue with the injection pump itself. Good luck and let us know if you have any other questions or what you come up with.

  26. Hello,
    2006 ram 3500 5.9 cummins, truck was working fine, set up for two weeks, drove on third week for about seventy miles round trip. probably ten miles from house sitting in traffic check engine light comes on. truck never ran rough or anything. probably had about a 1/4 tank of diesel. pull code and it is P0148. I changed pressure relief valve first. truck just cranks and no start. a week later changed the fuel control actuator, and same thing truck cranks but wont start. If it helps on cool mornings when i start truck it will rough idle and blue smoke for about 30 seconds then clear up.
    Thanks in Advance

    1. Thank you for the inquiry. We’re sure you are aware at this point, but just in case, P0148 specifically means High Pressure Common Rail Checksum. In other words, it means that the desired pressure as commanded by the ECM is not the actual pressure, which of course, could be a multitude of things. You’re on the right path by having replaced the pressure relief valve and the fuel control actuator. Because of the blue smoke, that leads us to believe its an issue with one or more injectors causing a high return rate, essentially creating a pool of fuel on top of the cylinder(s). However, it would still be a good idea to start with the simplest of things and check the fuel pressure (low side) as described in the original post. If that returns normal, we would suggest having a fuel return rate test performed to confirm the integrity of the injectors.

  27. 03 5.9 driving at 50mph truck acts as if it jumps out of gear I pull over turn it off checked it out saw nothing came lose tried starting it and it took forever to start for a sec with pedal to floor ran for couplease sec died now want crank and hole truck shakes when trying to crank turns over really fast pulled codes p0700 p0336 p1652 p1687 p0205 any ideas where to start contact me at 2258108018 I can explain better thanks

  28. 2005, will not start, but if you let it sit it will. Had it in a garage for fan bearing, mechanic cut wires in front of fan

    1. While we would recommend reconnecting the wires at the fan, it should not be preventing the truck to start, worst case is you’d typically get a P0483 or P0480 code from the wires being cut. Depending on how the truck had been running before the no start symptoms started up, its sounding like injector failure. In many instances, the longer the truck sits, it will become easier to start due to a high return rate of the injectors. With a cold cylinder, the air is more dense and will light off a little easier than a hot engine. We would recommend an injector return rate test first and foremost.

  29. my husband has a 03 5.9 cummins automatic
    the truck will start with and with out the fca plugged in at MAX fuel pressure
    I have new cp3
    connector tube
    cam shaft position sensor
    fca rail sensor
    it throws 4 codes
    1. cam shaft position sensor range performance
    2. cam shaft position sensor A circuit
    3. sensor reference b voltage low .
    4. fuel rail pressure circuit high.

  30. my husband has a 03 5.9 cummins automatic
    the truck will start with and with out the fca plugged in at MAX fuel pressure
    I have new cp3
    connector tube
    cam shaft position sensor
    fca rail sensor
    it throws 4 codes
    1. cam shaft position sensor range performance
    2. cam shaft position sensor A circuit
    3. sensor reference b voltage low .
    4. fuel rail pressure circuit high.
    thanks in advance !!

    1. Thank you for the inquiry and sorry to hear about the issues with your husband’s truck. Curious, did it have these codes before pump, injectors, etc. were replaced, or is this merely what its throwing now? What was the reasoning for changing the parts in the first place as you say it “will start with and without the FCA…..” or would it not start in the first place? As far as the rail pressure circuit high code, that’s caused from starting the truck with the FCA unplugged. If the cam shaft related codes were present before swapping out the cam sensor, its very possible you need a crankshaft position sensor, as these two work off of one another. Basically, you could throw a cam code, when its actually the crankshaft position sensor. Overall, if you can give us a little more information or you’re welcome to give us a call and we can see if we’re able to help diagnose a little further with you.

  31. 2003 dodge 2500 Cummins. Won’t start. Replaced fuel filter. Can’t get fuel into filter canister. Replaced fuel lift pump in tank (factory upgrade previously done). Still can’t get fuel into filter canister. Seems like pump comes on but won’t prime and truck still won’t start. Ideas greatly appreciated!

    1. Would the truck not start only after replacing the fuel filter? If this is the case, then you typically only need to bleed the air out of the system. However, if it wouldn’t start before the fuel filter, then the health of the previously installed lift pump would be the first place to check, as we’ve seen these also fail numerous times. They don’t fail as much as the block mounted pumps, but still definitely fail. You should be able to bump the key and listen for the hum of the pump at the fuel tank. If you can’t hear anything when bumping the key, then its likely the pump is bad or just the power supply to the pump (like a bad fuse). Also, if your pump is running, then check for any air leaks before the filter. Let us know where you’re at and good luck.

  32. my engine revved hi for a couple of seconds b4 i shut it off and now wont start. had everything checked and they said there is no power going to the injectors. does that mean my pcm/ecm is bad?

    1. While its definitely possible your ECM is bad, its not very common. Does the truck crank over, just not start? How many miles are on the truck? One scenario that is more common and is inline with your symptoms is a failed Fuel Control Actuator (FCA) on your CP3 injection pump. When the FCA fails, or loses power from the ECM, it loses its metering capability, meaning the CP3 now runs at full bore, thus your RPM’s quickly increase to high levels. Then, what can happen is because of the excessive pressure, it actually blows out the Pressure Relief Valve (PRV) on the rail. When the PRV fails, your fuel rail cannot maintain adequate pressure, thus the truck won’t start, but will still crank over. You can also give us a call and we can discuss more about the symptoms and other possible fixes. Good luck getting the truck running again.

  33. Hi!! Thanks for all the advise you have given to everyone now I guess it’s my turn to try and stump you…. I have a 2006 ram 3500. My initial issue was a rough idle, replaced the fca and did a general service oil filters etc. No change. During winter started having trouble starting and while out of town ended up replacing 1 battery ( I know I know need to do both) but at the time I could just do 1…. anyways truck still had a rough idle and then would not start. Tested injectors they were bad and replaced all 6. Everything went fine during replace all torqued to specs etc. Went to start afterwards and for some reason it shorted out my grid heater literally melted the metal connector between the 2 bolts then fired right up. Idle sounded great everything sounded perfect ran great everything… now to my current issue. The next day after it sat all night wouldn’t fire at all just cranked and still having this issue. If the truck is cold ( hasn’t ran for 6 plus hours) it has to have either to start I’m fully aware of either being bad…. once it’s started with either I can drive to work shut it off and 4 hours later it will start right up. So the start issue is only when the motor hasn’t ran for 6 plus hours if the motor is warm I have no issues. I have just left my grid heater how it is it’s been 60 plus degrees right now and mid 30s at night. I have gone back through and re torqued all the tubes from the injector install just in case it was bleeding fuel back and no change. Today had my other battery tested and they said it’s bad ( won’t even register on the meter at napa) so long story short my question is would my grid heater shorting out cause my issue or would 1 bad battery cause this issue or something else you can think of? I’m definitely planning on replacing my other battery soon I know that has to be done just not sure if I’m looking at another issue. Thanks for your time you guys are great!!

    1. While a bad battery can definitely limit the truck’s ability to start, it doesn’t really sounds like that’s the root issue. As long as the truck is turning over relatively easily, then that’s not it. It sounds more like a pressure relief valve issue based upon your description. Sure, if you’ve recently driven the truck and the alternator has been able to charge the batteries, being able to crank it immediately following will be easier. In order to prove this theory, you could let the truck sit for the 6+ hours as you’ve described, but then have another vehicle running next to yours and connect the batteries with a pair of jumper cables (go to your known bad battery) and see if the hard start issue is still there. Presuming it is, your next thing to do would be to take the return line off of your pressure relief valve and see if there’s fuel sitting in top of the relief. If there is, its possible that’s the issue. Next, try and crank the truck with someone watching the top of the relief valve (note, do not stare right at it as fuel may spit out). No fuel should come out of this relief valve when cranking. If fuel comes out, you should either get a new pressure relief valve, or replace it with a pressure relief valve block off. Anyways, that’s where we’d go next in diagnosing this based upon your description….GOOD LUCK!

        1. Thank you for the feedback, and sorry to hear the PRV Block Off didn’t solve the issue. Presuming the truck is turning over relatively well with the one suspect battery, the next place would be to check is the fuel pressure off of the lift pump. In order to gauge this, you’ll probably need to hit it with ether again to see where its at. One important thing as mentioned in the original post, is to watch it not only as soon as the truck is started, but while its running and during start up. Many times, the stock lift pump will show adequate pressure as soon as you get the truck fired, but then fall off completely after 30 or so seconds. When this happens, you can get drain back of the fuel, giving another reason as to why the truck won’t start the longer it sits. I wouldn’t say these fuel systems are necessarily finicky, but there can sometimes be several reasons for a similar symptom.

  34. I have a 03 dodge cummins with no start cold or hot .I can take the fuel filter out and wipe the bole clean then more than likely I have to start it with wd 40 but then it starts fine for several times after that 2 to 3 sec. every morning I even let it sit for a week and it started right up .Then I run it to town 10 mi. .Then slowly slowly, longer starts till [ no start] until I mess with the filter again .ps new filter .cleen fuel. new in tank pump.

    1. This seems like somewhat of an odd situation, but lets see if we can figure it out. It doesn’t sound like its necessarily the action of wiping out the fuel filter base that’s allowing it to start, but rather the WD-40. Overall, it feels like a pressure relief valve or injector issue. In one situation, if the truck is sitting for longer periods of time, the fuel is essentially draining back from the rail, and creating an air pocket in the rail. Once you hit it with WD-40, its enough flammable gas in the chamber, it fires the truck off of WD-40, bringing fuel into the rail since the CP3 is moving now. Then, the longer it sits, it drains back again. The next theory would be high return rate on the injectors. Basically, the same theory, but instead its draining fuel into the piston bowl. But with this one, usually the truck will pour white smoke when you’re trying to start it as the bowl has a considerable amount of fuel in there. To test the PRV, remove the return line on top of the PRV and crank the truck with someone watching the valve (don’t stare at it as fuel may squirt out). At crank or idle, no fuel should be coming out. If there is, you need to either replace with another pressure relief valve or with a PRV block off. In order to get to this point, you may need to use something like ether again to fire the truck to even see the fuel coming out.

  35. 2003 Cummins 5.9, 167,000 miles. Long start when cold (less than 50 degF), and no start (unless you use starting fluid) when it’s really cold (less than 25 degF). If you keep it plugged in, it always starts, though still can require a long crank. I’ve performed every single test you suggested, and everything is in spec, I also installed a PRV block-off. I ran the return flow test several times and it’s returning 160mL in one minute. I will say though that I’ve only been running it at idle (so a little less than 1000 RPM). Should I re-run at 1200 RPM? Also, I’ve seen other sites that say to remove the FCA harness when running this test. I tried that once and had 350mL of return in 30 seconds. I also purchased a blocking tool to block each fuel rail feed tube connection one at a time to see if there’s a leaky injector. I’ve only been able to check 3 so far (2 are tough to get to, and one fitting is seized up). Two of the injectors accounted for 22mL each, and the 3rd account for 37mL.

    1. Based upon the numbers you’re giving us, you’re at the absolute maximum acceptable range of return flow and that’s at below the recommended RPM range. If you were to bring it up to 1200 RPM, you’ll be getting over that 160 mL threshold, meaning that most likely your injectors are the culprit for the hard/no start.

  36. Hi, I have a 3500 5.9 2003 Ram p/u.
    The other day it seemed like it was running out of fuel (full tank) it stalled and after several minutes of cranking it started and I was able to get home.
    I have no power at relay (other than hot from battery) and FUEL GAUGE is dead…..?
    In tank pump. Working . Sounds electrical

    1. Hi there and thanks for the inquiry. Yes, it definitely sounds electrical. The fact that the fuel gauge is not working should not be the culprit for the hard / no start. However, it could be an indicator of what is causing the issue. Because there is a joint wiring harness from the fuel tank’s basket which stores both the fuel level sending unit and fuel pump wiring, that would be the first place to inspect for any corrosion or breakage of the hot lead and/or ground. It will probably require a visual inspection of the entire harness and you could also run a continuity check of each wire.

      1. So, hot wired fuel pump, works,
        checked relay, working.
        Ran jumper ground to pump, works but still no gauge. Sounds like a ground problem, ( I get a slight movement on fuel needle JUST a tiny bit).
        There’s a bundle of ground wires bolted to front fender, dose this bundle run to rear of truck among other places?
        Not sure what to think about gauge as it is a separate circuit I believe, but must end up going to ground somewhere.

        I,ve checked grounds and plugs/connections. Cleaned battery posts.

        Today, no left headlight and no parking lights. …update, headlight came on then went off again. Maybe ready to burn out, hum
        Was thinking of a local ground to frame at the rear. Can black wires with a color tracer be grounded to frame.?
        Long winded I know but may help. Thanks for your response and cheers

        1. This definitely sounds like a grounding issue. There’s several physical grounds on the truck, and one that goes forgotten sometimes is under the bed on the under side of one of the box supports. I’ve personally seen a truck go completely haywire when this strap was not hooked up, also check the ground strap to the front inner fender from the battery. These need to be clean, even take the one at the fender and scratch up the surface of the paint. Please also make sure your battery terminals are free of corrosion. To answer your question about the bundle of wires, if its the one I’m thinking about, yes, it goes to the rear of the truck, ending at the taillights and trailer wiring. So again, start tracking down all physical grounds and cleaning them up, making sure the wires aren’t broken anywhere. Good luck.

  37. Okay, so I have a 2012 6.7 Cummins. Put an Arson 3 kit on cp3. Truck wouldn’t start. Put stock actuator valve back on and started right up. Decided a week later to put a plug in my rail because truck just seemed to want more fuel. It would go into limp mode at higher speed. It would just over rev. And I would lose power. Anyway, couldn’t get the relief valve out to save my life no matter what I tried. Ended up having to take the whole rail out and use a vise. Re installed averything along with a big line kit from glacier. Now I’m getting fuel through the added mk2 filter and nothing out of the supply line to the rail. Truck won’t start. Just cranks.

    Also, when I was fighting the reief valve I was using a cheater and slipped grounded my wr much and cheater and hitting the positive post in my battery…. (what more could go wrong right?). So onvioulsy big arc on that one… not sure if I shorted something or what the hell is goin on.

    Anyway. I’m out of ideas. Any help would be awesome.

    1. Sounds like you’ve got your hands full! Regarding the initial issue, we have seen failed FCA’s right out of the box with several manufacturers of aftermarket kits such as this. We’d recommend getting with the manufacturer and getting a new FCA based upon the information you’ve provided. As far as the slipped wrench, that most likely didn’t cause the issue, it happens to the best of us and rarely causes a real issue. You don’t mention that you’ve bled the system to remove any air, and it sounds like what the cause of your most recent issues at least. If you haven’t already, remove the return line for the injectors at the back of the head and bump the key to engage the lift pump to push fuel without air blocking it. Let us know if you’ve already done this and we can take it from there. Good luck!

  38. I have an ‘06 5.9 that won’t start. Iniatially it would die when slowing down to stop or turn. After draining the fuel filter it would eventually start and run fine at highway speeds. Then after 10-15 mins die again when slowing down. Eventually it would not start at all. I’ve replaced the fuel filter and it still won’t start. The fuel filter refills when I let the pump run to prime it. It has fuel in it every time I drain it. Your help would be greatly appreciated

    1. Thanks for the question, lets see if we can help figure out your issue. Based upon what you’re saying, the entire system is having difficulty maintaining pressure since its dying after you’re essentially reducing the throttle input / desired amount of fuel volume. The first thing to check if you can is actual lift pump pressure. What we’ve seen time and again, is that even though its pumping fuel, its not enough, and it will “give out” just driving down the road. Then, you give it some time crank and repressurize the system, and it will keep up for a little longer. Because of the high failure rate of the lift pumps on these trucks, that would be the first guess. Secondly, you could have a pressure relief valve that’s allowing excessive fuel return. This one isn’t quite as likely, though because of how its dying as you’re slowing down. Typically, this valve will return more fuel as more throttle is input, but yours sounds like the reverse. However, this can be a finicky system, so it would be a good thing to check, and its easy enough to do so. Just remove the return line off the top of it and crank the truck. See if any fuel is spitting out of it while cranking, if there is, it needs to be replaced or blocked off. These would be the first two things to check over that are the biggest culprits. Let us know what you find and we can take it from there.

      1. As far as I can tell it seems to be the lift pump. I’m getting fuel to the filter, but when I take the cap off the fuel tank and bump the starter I can’t hear the lift pump running. I guess the injection pump is drawing fuel to the filter.

        1. Yes, if you’re able to get the top off of the fuel tank and you’re not able to hear any “hum” from the lift pump, most likely its dead. Your best bet would be to replace with a FASS or AirDog system so you don’t have to worry about the issue again. And yes, the CP3 injection pump does have the ability to suck fuel, just not very efficiently, so that’s probably how you’re getting fuel to the filter. Let us know if you’ve got any other questions and you’re also welcome to call in and discuss.

          1. Update. Replaced the lift pump and the truck runs great again. Thanks for your help.

  39. Have an 07 5.9 today it just wouldnt start after shutting off for 2 minutes and the rest of the day on a trip if shut off has also had longer cranking lately during start up, cranked like crazy but no start, lost prime. Can hear lift pump coming on and if crack drain valve i get a good stream coming out with pump on. No visible fuel leaks, injectors are farely new, we got it running instantly with small shot of starting fluid (had no choice 300 miles from home im Michigan’s U.P.) ran fine driving and idling never skipped a beat.

    1. This is showing all of the signs of a failing or failed pressure relief valve. You can either replace the valve with a direct replacement, or some will take the route of installing a pressure relief valve block off. This part has a high failure rate, so is most likely causing the issue. The factory valve has a light weight spring that relieves pressure at a predetermined level, but as that spring fatigues, it will bleed off prematurely, causing it to lose prime. Especially since you have newer injectors, its highly likely this is the cause. The blog post explains how to test this and confirm so you can be more guaranteed. For reference, below are links to both the replacement relief valve, as well as a block off. Please let us know if you have any other questions and we’d be glad to help.



  40. 2010 Ford F-350 with 2003 5.9L 24v Cummins swap. Fass Titanium Fuel Pump w/ New Filter & Seperator

    My Fummins cranks, but will only start with ether. Once started, it idles and runs fine, but will not restart unless I spray it again. I’ve cracked open the PRV, cranked several times and no diesel leaks from the top banjo bolt. I’ve capped each injector separately with the miller injector block tool and cranked, but still no luck. The FCA was unplugged and no luck. I’m getting good pressure from the FASS to the CP3 pump, but yesterday I noticed if I remove the CP3 output line that goes to the fuel filter block off plate and crank the engine, the fuel just drips out. Fuel system has been primed and there’s no air. Is the CP3 known for getting clogged? If in fact it is clogged, how does it start and run with the use of ether? I feel the clogged pump would starve the rail/injectors and cause the truck to run like crap.

    Any input would be greatly appreciated.

    1. First of all, sounds like a very cool conversion. Most opt for the simpler 12 valve conversion, always good to see a common rail conversion. In regards to your issue, it sounds like you may have too much injector return flow on 3 or more injectors. Blocking off single injectors will isolate the issue if only one or maybe 2 injectors were returning to much. If all of them are returning excessively, it typically won’t matter if you block one off at a time, and you’ll need to measure the return flow for all 6 injectors.

      1.) Maximum allowable leakage for all injectors combined is 160 ml per minute: check when coolant temperature is above 180 degrees, 1200 rpm and fuel rail pressure is equal to 20,305 PSI.
      2.) If you have a no start condition, maximum allowable return is 90 ml per minute at 200 rpm cranking speed, be careful not to over heat the starter during testing.
      Good luck, and please let us know if you have any other questions.

  41. Hey yall,
    Got an 06 5.9. Had a bad lift pump, replaced it and immediately started having a long crank issue. Truck always starts but turns over longer than it should and runs rough for 3-5 seconds with a puff of whitish smoke. Only when sitting for several hours though. No issue when warm, fires right up. Also, I have noticed a lack of power. No codes, truck is mostly stock with the exception of an Edge, 250k miles, only ever replaced one injector and had the issue before that.

    1. First things first, we’d recommend pulling out the Edge and returning to stock, just to make sure there isn’t some type of failure in the circuit board there not allowing the rail pressure or MAP sensor (and injector harness if its a Juice with Attitude and not an EZ) to read properly. Once that’s returned to stock and if its still doing the same thing you’re going to need to run an injector return rate test. At 250k miles, its likely you need to replace the rest of the injectors. The original injectors in the 2004.5-2007, sometimes called the “505” injectors had an exceptionally high failure rate, enough so that Bosch, the original manufacturer, revised them.

  42. Hey yall,
    I have an 06 5.9 that had a bad lift pump, replaced that and immediately started having a long crank issue. Truck always starts but turns over longer than it should and runs rough for 3-5 seconds with a puff of whitish smoke. Only when sitting for several hours though. No issue when warm. Truck has 250k miles with only ever replacing one injector and had the issue before that. All stock except for Edge and exhaust. I’ve noticed a lack of power too. Not much but enough for me to feel.

    1. Thank you for the inquiry. Your symptoms definitely sound injector related, especially with the model year of the truck and having 250k miles. What’s interesting is that it only started after replacing the lift pump. Depending on how long this has been going on, its possible you introduced some air into the system which ended up putting the final nail in the coffin for your other injectors. The real way to confirm this is to have a return rate test performed on the injectors, but again, they are delivering all of the typical symptoms. That is the first place we’d recommend checking and go from there. If you need any recommendations on quality injectors or any other questions, feel free to reach out to us.

  43. Have 2006 dodge 3500 5.9 The coil light is staying on constantly ,the grid heater is not working. I have change out soliniod /rely with a new one with same result. bench tested grid heater to power supply and it glows red quickly and appears to be working fine. Also there is a constant clicking sound ( like a relay ) at a fairly fast rate coming from drivers side back or lower back of the motor when key is in the on position (not running )have never noticed this before and is hard to locate exactly where it’s coming from. Having hard starting issues and stalling at low rpm. If you get out on the highway it seems to perform okay. Coil light will still be unlimited ,not sure if this causing some kind of limp mode ?
    Any advice would be great . Thanks for all formentioned information on fuel system troubleshooting , it has been really helpful .

    1. HI there, thanks for checking in with us and the accolades. In terms of the coil light staying on, the first thing to check or replace would be the IAT (Incoming Air Temperature) sensor. If I remember correctly, the IAT must sense 55+ degrees Fahrenheit to trigger the grid heater. If its malfunctioning, then it could be causing the light. Also, check the continuity on the grid heater wire as we’ve seen those get corroded out for various reasons. In regards to the clicking, if you’re not able to follow the clicking sound, you could start pulling fuses one at a time to see what essentially causes the clicking to stop and then locate it that way. Hope this helps, if you have any other questions, please feel free to contact us or reply to this post.

  44. Hi, I have a 2003 with a 5.9 Cummins. It starts and idles fine but after about 5-7 mins. it kills just as if you turned the key off. The truck will crank right back up and do the same thing repeatedly. If I do try to drive the truck while it’s running it bucks and barely wants to run. I have dropped the tank to make sure that the pick up screen is not clogged, there is no lift pump in the tank, I have changed the filter housing mounted lift pump, a new ful filter and FCA. No check engine light on but did hooked a scanner up to the truck and got codes P0462/P0463 fuel sensor voltage high/low, which I think is why the fuel gauge doesn’t work but truck does have fuel in the tank, and P0700 transmission solenoid not sure what that means. Maybe because of the bucking when I try and drive but don’t know if that would cause the killing issue when idling. Been trying to figure this out for a good while now any help on what to look for or check would be greatly helpful and appreciated.

    1. The P0700 is a general code that is just telling you that there is an issue with the transmission. Unfortunately, you could have a few things going on here. I would be looking at the high pressure side of the fuel first and foremost. Checking the PRV and also doing the injector return flow test as described in the original post would be the first items to check. You could also have the torque converter stuck in lock up or something causing the bucking and killing of the engine, but being its so random and its fine when you first drive the truck, its more likely on the fueling side. Good luck and let us know what you find, please.

  45. Still troll shooting the 06′ but have different issue with my 07.5′ 6.7 3500 . Have no power to the lft pump ,tried to scan DTS codes with my smarty ,but comes up (wrong com error) this smarty has been vin coded to this truck for years. I’m hoping my ECU didn’t give up th ghost . All fuses good checked all wiring for breaks and could not find any visible .died on flat paved road.bench tested lift pump and it work fine and tried a new one in the truck to no avail. Any suggestions to check or try would be greatly appreciated.
    Love my cumminsis ,but not having good luck lately .thanks again, Shawn B

    1. Definitely sounds like you’re having some bad luck lately! Since you’ve got a Smarty, the first thing we’d recommend is to just try and tune the truck with the Smarty to confirms its responsive and hopefully load a program to “wake it back up” so to speak. However, if the ECM is non-responsive, it will not let you load it in. Otherwise, if you have, or can get your hands on a scan tool, try to connect to the ECM. If you’re not able to, check over your power and ground for the ECM and all connections to both batteries to ensure nothing is corroded or shorting out. Good luck, let us know what happens, please.

      1. 06 5.9 link to a YouTube video .my truck is making this exact sound (ticking or clicking) ,but sounds more like it’s coming from the back of the engine rather than the grid heater .going unhook temp sensor from Tranny and look for code#712 also the TTVA where the shift cable attaches has a constant buzzing at the same time (key on not running).

        Link :long cold / no start below.

        Will do with 07.5
        Thanks again ,this is the best diesel blog on the web!!

  46. Hi there, 06 3500 5.9 cummins update.cleared trouble codes and coil light stays off changed grid heater relay and is working .pulled top 30 amp fuse number 42 ( diesel PCM ) and the clicking noise from back of motor stopped but then sound like the lift pump surging on and off when pulled ,clicking sound returned as soon as the fuse was reinserted. Getting code #713 ,clear code and comes back soon as key is turned on.
    Engine stalls at low RPM or shifting into reverse or drive .clean fuel ,new lift pump ,new filter and changed out AFC.

    1. Okay, so it sounds like the grid heater is handled. The P0713 code is a trans temp sensor too high, which can be kicked when the wiring is shorted to ground, or the sensor itself is grounded. We’ve seen this wire get pinched when reinstalling the transmission pan after a service, and this code will cause a ton of issues. If you determine that the issue is constant, unplug the temperature sensor at the transmission. After you’ve done this, you should ordinarily return a code P0712 (low temperature error). If you receive that code back, then the issue is inside the transmission (either the wiring inside or the temperature sensor itself). If you still receive a P0713 after clearing with the connector unplugged, your short circuit is external to the transmission. The stalling you’re experiencing could very likely be caused from the transmission being stuck in lockup or other issues with the torque converter.

      1. 06 dodge 5.9 disconnected trans temp sensor .cleared DTC codes .put key to on position ,the horn and the flashers went of once .code #713 returned. may you be able to elaborate more about lockup or torque conveter issue.
        Thanks, Shawn B

        1. If the torque converter is in lockup, its kind of like when you start a rig in a high gear without using the clutch, or coming to a stop, again, without the clutch. The engine is getting all of its power through the transmission, making it buck and lurch when it should be slipping. The P0713 code, as mentioned, is excessive transmission temperature, which extended periods of high trans temp are the number one killer of transmissions, but your no start issue coupled with the sounds its making definitely does not sound anything transmission related. Right now, it sounds like there are a multitude of things going on, honestly, which is starting to make me wonder if there simply isn’t an issue with either the ECM or a general grounding issue. On one hand, you’ve got the trans issue, on the other, a fuel related issue, then the grid heater you mentioned. All of those are relatively unrelated, but electronic at the same time, so again, possibly the root cause of all of this is really in the computer. Diagnosing an ECM does require a professional grade scanner, but what you can do is visually check over the grounds, the alternator, and power to ensure there’s no corrosion, wire breaks, the usual. I apologize this one isn’t a straight answer, but again, seems there are several things going on here.

  47. I have a 2004 Ram. No start. Fuel psi on scanner always reads 340 psi all the time. I followed your excellent instructions all the way up to the injector fuel return volume. I was getting over 300 ml fuel in 1 minute cranking. This is where I am stumped. I removed all the fuel injector lines and capped off the fuel rail. Even with all injectors lines disconnected, I am still getting 90 ml fuel return in 15 seconds. I know I have the correct line from the back of the head. Any idea where the fuel could be coming from? A small amount of fuel will trickle out of the return line even without cranking, when the lift pump is running.

    1. Erik, thank you for the inquiry, lets see if we can get to the bottom of this. First of all, we need to get some clarity on one thing you mentioned. If you had removed all of your injector lines and capped off the fuel rail, you shouldn’t be getting any return as there would be no fuel going to the injectors whatsoever. So, when you say you’re getting 90ml of fuel return in 15 seconds, where are you measuring that fuel from? If you really are measuring return fuel with the injectors disconnected, you’ve got an awful lot of fuel sitting in your cylinders. In terms of capping off the injectors, that’s really only for determining an issue with a single injector in which you cap off one at a time and run the test six different times (one for each injector). Maximum leakage for a no start condition is 90ml per minute at 200RPM cranking speed, so if you are somehow getting 90ml in 15 seconds, you’ve got highly excessive return, possibly caused by the fuel control actuator overspeeding the CP3 literally just dumping fuel coupled with bad injectors that are letting it overflow. Otherwise, it could easily be that your injectors are completely shot.

  48. Thank you. Yes, I started by capping 1 injector at a time to find which 1 could be causing the leak down. When #1 made no change in the fuel return volume, I proceeded to cap #2 (#1 still capped as well). I continued this way checking the fuel return volume each time down the line. By the time I was done, all 6 injector feeds from the fuel rail were capped off, with the same results. Maybe I am recovering the fuel from the wrong hose? I am connected to the fuel line that comes from the back of the cylinder head. I squeezed the plastic hose clip and pulled off the rubber hose that returns back to the fuel tank. I connected my test tube to the metal side of the hose that goes up the back side of the filter housing and continues to the backside of the cylinder head. (I believe I connected it to the correct line that you referenced in your tutorial??). I agree that there should be no fuel getting to the injectors with all the lines capped. I don’t think I have any fuel sitting in the cylinders because I am not getting any fuel or smoke coming out of the exhaust when cranking, and there are no sounds of combustion. The other thing is that the scanner is showing only 340 psi at the fuel rail. With all the injectors capped, shouldn’t I be showing significantly higher psi if the fuel control actuator was over speeding?

    Would you please try and explain the location of the injector fuel return line a bit better so I can make sure I am connected to the correct line. Thanks Again for the Help.

  49. I did some checking and found out that the fuel return line is connected to both the cp3 return and the injector return. It requires Miller tool 9012 to be installed to isolate the cp3 return from the injector return. This is why I am getting high fuel return volume even with all injector lines capped off.
    Since I don’t have tool 9012, I removed the rubber hose from the cp3 return and routed it into a container (this isolated the cp3 return from the injector return). Now, I am not getting any fuel from the injector return fuel line while cranking. Time to reinstall all the injector lines and start the test all over again.

    1. We apologize for the delay in getting back to you, phones have been ringing off the hook the last couple of days. From the sounds of it, you’ve got the correct return, however, it still sounds like you are capping off all injectors at once by the time you are done with the procedure. You should only be capping one injector at a time to see if the overall fuel return changed with each capped individually, so that you’re able to isolate one injector that could be causing the high return. If all of a sudden, once one is capped compared to another (say #4 versus #5) and your excessive return goes away, you know that it was that particular injector. It sounds like your overall fuel return is excessive, signifying that all of the injectors are producing an excessive return in most cases (which isn’t abnormal in any way, typically they all tend to fail together). As far as you only reading 340 psi at the rail with all six injectors capped, we are trying to determine what instrumentation you are reading that with. If there is a massive amount of return, then its not going to build any usable pressure, but it seems like it should be a lot more than 340. Overall, based upon the information we’ve been given, it does sound like an injector issue.

  50. I have an 06 Dodge 2500, lots of surging and will die sometimes at a stop. I have changed the TIPM, fuel rail control sensor and the FCA, still have the same issues. I tried the test on the FCA of unplugging it and the truck did start but its a new Boche FCA(could it still be bad? I do have a lift pump mounted on the frame and when it dies, the lift pump will run for an extreamly long time(20 to 30 seconds) then cut off. When you start the truck, it will surge, rough idle and die back out again, If you turn the key off and let the lift pump run for about 10 to 15 seconds, it will start up a little smoother. Any suggestions?

    1. Thank you for the inquiry. The first thing to check would be what, if any, codes you are throwing (Check Engine Lights). Those may sometimes give a definitive direction on the root cause of the issue. As far as the FCA being unplugged and it starting, presuming you meant it wouldn’t start with it plugged in, but then it did start once unplugged? That could potentially be a sign that with all of the extra pressure at start up (due to the FCA being unplugged), it was able to overcome the reason its not starting. This could likely be if the Pressure Relief Valve (PRV) is opening / fully open when cranking, causing it to bleed excessively out of the rail when the CP3 is cranking normally. That being said, you should check lift pump pressure first and foremost, then move onto the pressure relief valve test, followed up with the injector return rate test as described in the original post. Good luck with the diagnosis.

  51. Hi excellent Diesel Dudes,
    No start Re: 2006 w/5.9 . Fixed bunch of issues with truck and have all codes cleared. There was a bunch of things that were preventing me from proper diagnosis of fuel system . Have clean tank,new lift pump ,new filter installed , CP3 pump and FCA from my 6.7 .PVR blocked off . Okay now will start with a wisp of either, my scan tool will allow me to read fuel pressure. At idle running 5600 – 5900 / full throttle over 21000 psi .when i shut truck off it drops right down to right away to 20psi not holding the rail pressure .have a flat deck on it with access to the fuel return line is pumping a lot back to tank while running. Just wondering when i shut truck off . ” where my rail pressure is giong “. (back through the CP3 pump return or or injector return at the back of the head ?) im told the rail pressure should hold 500 psi at rest and check valve at the injector return (back of Head) only holds at 14 psi ,not sur if this correct or not.
    “Almost there” , thanks for your wisdom here.
    Shawn B

    1. This is really sounding like you’ve got a high return on at least one injector. IF the return line you took off was the injector return line, that would verify that the injectors have an excessively high return. You can cap off each injector individually to give a better idea of whether the issue is from a single injector or multiples. At idle, you shouldn’t have any return.

  52. Re: 2006 dodge 5.9
    More testing here .
    While truck is running at idle showing 5600-5900 psi rail pressure . I unplugged the FCA and there is no change in rail pressure (no spike) and will stall within 30-40 second after disconnecting.

    Will stay running if not diconnected and idle fine and maintain rail pressure till shut off in wich it drops right away to 20 psi.

  53. Re : 2006 dodge 5.9
    Getting truck to start with a whisp of either now.
    All code have been cleared.
    Showing rail pressure 5600-5900 on scan tool while at idle and up to 21000+ at a full trottle tap, doesn’t seem to misfire no smokes.and can take load without fuel pressure drops.
    When the the truck is shut off rail pressure drops immediately to 20psi.
    Will not start withe FCA unpluged
    If i unplug the FCA at idle there is no change in rail pressure ( no spike ) and will die 30-40 seconds after.

  54. Re:2006 dodge 5.9
    Additional: truck will run fine with FCA pluged in.
    PVR is blocked off.
    Was told at a static or non running state should maintian 500 psi rail pressure and the the injector check valve at the back of the head only holds back about 14psi ( is this correct ? )
    wondering if im getting bleed back through the CP3 return some how or excessive retun at the injector check valve.
    When truck is shut off rail pressure drops immediately to 20 psi .
    Going to injector return test. Still dont understand FCA issue.
    Thanks again for your awesome wisdom Diesel Dudes!!

    1. Thanks for reaching out to us and apologize for the short delay in responding. Alright, so a couple of things that are throwing us off a little:
      1.) when you unplug the FCA, your rail pressure should be jumping considerably because the CP3 is no longer being metered, which could mean that the CP3 is actually bad
      2.) 14 psi at the back of the head is extremely excessive
      3.) the 6.7 FCA has a different fuel table compared to the 5.9, so we wouldn’t recommend running that one and honestly not sure if it will even be a good piece to test with, but the fact that you’re still not seeing any change in rail pressure with it unplugged makes that a moot point

      Our recommendation to get started would be to first start with the injector return test as that’s the most likely culprit for the excessive return. You could / should also confirm the torque on your connector tubes which could also be causing the high return rate. There was even a TSB issued years ago for loose connector tubes that can easily deliver similar symptoms as the tube is not seated into the injector, which then fills the crankcase with fuel. Good luck, let us know what happens after the return test.

  55. Re: 2006 5.9′
    No fuel in oil.
    Did injector return test
    Torqed injector tubes
    Cranked till saw fuel before starting test..
    Did a 30 second crank test recovering about 80 ml from the injector return line.
    Seperatly at the same time the return from CP3 recovered about 460ml.
    Scan tool showing maximum rail pressure when cranking between 500-700 psi. Then like i say when you stop comes to resting pressure of 20 psi
    -only have one block off tool.
    Did block off each injector at a time and cranked could not achieve more 500-700 psi while capping off each injector.
    Wisp of either though will get her over the hump and run good when running?
    Ps: I’m 200 miles from nearest parts store or garage , so just using what I have out here .Getting towed to the dealer is not an option.
    Thanks again guys.

    1. This definitely sounds to be injector related. The maximum return rate is 90mL at one minute of cranking, and you’re seeing nearly that amount in 30 seconds of crank time.

  56. i have an 05 5.9 cummins. i have replaced the in tank fuel pump, fuel filter, fca. i have also ohlmed the injectors and they where good. im still not getting desired fuel rail pressure when cranking. every so often it will build enough pressure. what could be the cause of it not building pressure? is the pressure relief valve?

    1. This could very easily be the pressure relief valve. Go ahead and remove the return line and follow the instructions laid out in this article. Its a very common issue on these, and you can either replace with a new PRV, or install a PRV block off. Please let us know if you’ve got any questions.

  57. My son in law has a 2004 Dodge Ram 2500, 5.9 Cummins, 4×4 auto trans. Engine died. Wouldn’t crank. Towed pickup home. Fuse #20 engine run/start was blown. After replacing fuse engine cranks. Cannot read codes with my scanner or by cycling ign. Switch. . Guages don’t function. The overhead display is dead. Ther is no power to the #28 fuse, Cluster, Overhead Power, 4×4 Switch.

    1. This particular situation definitely does not insinuate a fuel related no-start issue, but sounds more like a TIPM. The TIPM is essentially the electrical box where all of the fuses are located and they can become corroded or short out from the underside, as well as internally. This may sound strange, but try lightly striking the TIPM with the key in the on position and see if any of the lights that are not turning on at least flicker when its hit, as this is usually a good indicator of a small short.

      1. Thanks. That is what I had more or less figured out. After II added the Chrysler program to my Foxwell scan tool. I was able to communicate with the abs, fcm and transfer case modules. I am suppose I will need a DRB III scanner to program a new integrated power module.

  58. We have 2007 dodge Ram 3500 with a 5.9 cummins. When you are removing the CP3 pump, is there anything special about it besides pulling the gear off. Will it sit in front cover like other engines and stay in time besides making sure the nut doesn’t fall inside? Timing the pump or engine?

    FYI every time we had our issue with the no start. When we made sure it wasn’t anything else and new it was the pump, we would poor about 4 gallons of water on the pump than it fired up after each attempt. We made sure it wasn’t the FCA by following your test and by only poring water on it we cleared it of its failure. Not only till you pored water completely on the on the pump did it start. Hope this helps anyone else.

    1. As far as removing the pump, you want to be careful when you remove the pump nut in the timing cover. You do not want to drop the nut or the lock washer that sits behind it into the timing area. You would then need to use a gear puller to pop(I say pop because most of the time you will literally hear a pop) the gear off of the shaft. You would then remove the nuts holding on the back side of the pump to the gear cover housing. There is an o-ring seal that seals the front of the pump to the gear housing that may take some light prying to slide it out. These pumps are NOT timed to the engine so shaft orientation will not matter when installing the new pump

  59. After changing the fuel filter the fuel pump is not pumping and is not getting any electric? Checked fuses and solenoids?

    1. Hi there. More than likely, the pump is trying to work, but there is air in the fuel line. We would recommend cracking the feed line to the injection pump and cycle the key to turn the lift pump on. The air is more than likely between the lift pump and injection pump. Hope this helps, good luck.

  60. Will my fan clutch being unplugged cause no power to my lift pump. 2004.5 ram 3500 with pump in tank. New pump no power to pump before during or after cranking engine.

    1. I am not aware of the fan clutch being unplugged causing the lift pump not to kick on. Usually the fan clutches cause issues when they are plugged in and the wires short out and cause the whole bus to go down. I would be checking to see if you are getting power to the connector at the pump and go from there.

  61. Rebuilt my daf cf 65 220 isb paccar engine,but can’t get it to start,when I spray quick start in the inlet manifold the engine will fire but only for the time I spray quick start and it dies,the accelerator pedal also does not seem to respond when pressed when engine fires with quick start, meaning the engine will just idle but accelerator pedal not responding to make it fire without the quick start,any help will be appricisted

    1. It sounds like you’re not getting fuel to the cylinders, which is why the RPM doesn’t change when you open the throttle, so its just burning off the Quick Start that’s in there. First start with bleeding all of the air out of the fuel feed line and injectors, and possibly that’s all that you need. If it won’t bleed, you’ll also need a lift pump simply to get it to prime.

  62. I have a 07 3500 6.7l it has a lot of pressure in the fuel tank when opening the cap it spews no fuel comes out but does have a white smoke looking fog coming out. took cap of and ran it it still has the smoke foggy stuff coming out it sometimes cranks right up and sometimes it takes a couple times of trying to crank before it starts. sometimes it has white smoke but not all the time. some days it will run fine and others it dont run good at all cuts out and dies when you stop. sometimes while driving it jerks kinda like its trying to die but picks back up. sometimes it acts like its running out of fuel. i unplugged the FCA and it starts with lots of white smoke i only started it once with it unplugged.

    1. Hi there.The white “foggy stuff” you’re describing sounds like unburnt fuel, typical of a high return rate (injectors going bad) OR insufficient fuel pressure to the injectors, causing the fuel to not properly atomize in the combustion chamber. We would recommend to start with some of the basics. You’ll want to start off with the fuel pressure test to confirm the lift pump is indeed working, both at idle as well as under load. After that, test the pressure relief valve, which will follow the same procedure as outlined in this write-up (removing return line and checking for the presence of fuel on top of the valve itself). Finally, you will want to test the injectors’ return rate. The pressure you’re experiencing in your tank could be the result of a plugged vent line or an excessive injector return rate. Let us know how it goes and we can take it from there. Good luck.

  63. 03-24 valve with 362,000 miles on it went yo Florida and back 3400 miles now truck will not start in cold. have added road karo for cold weather still hard start. no problems when running. Q has the type of fuel we now are required to use be part of my problem? truck was designed to run on #2 fuel not this ultra low sulfur fuel.

    1. Thanks for the inquiry and sorry you’re having troubles with the pickup. While ULSD has been proven to not have as high of a cetane rating and obviously less sulfur, its definitely not the cause of your issues. The fuel companies add in the necessary lubricants to make ULSD as good as the previous LSD in terms of its lubricating properties. More than likely, you’ve got one of two issues. First and foremost, depending on how cold it really is, your grid heater may not be firing, and when it does get relatively cold (lets say around 20 degrees Fahrenheit), the truck will be very difficult / impossible to start. You should hear the relays clicking or you can check the wires under the intake manifold for voltage. Otherwise, if you’re able, bring the truck into a heated garage, let is sit under the ambient temperature in the charge pipe system “should” be warm enough, then see if it fires. The next thing you could be running into is a high return rate on the injectors or an issue with the pressure relief valve (both leading to inadequate pressure in the cylinders to allow for initial combustion). As temperatures drop, it effects combustion due to the air density change in the cylinders, thus any inadequacy of pressure can also lead to a hard/no start that’s only an issue when its cold. To test these, you can read through the article. Good luck with the truck and let us know if you have any other questions.

  64. A question I have is on the injector return rate test spec is 90ml. Is that just the 90ml for all injectors combined or 90ml times 6 injectors? Thanks! Great article.

  65. Hi Josh, lots of great information you have put together…thank you!!
    What i see, these people are getting great help with advise your giving.
    I think you should explain them them on how much money they would save by doing regular maintenance, like oil changes sooner, using the right filter and correct oil for there vehicles…There having many fuel problems, i just wonder how often they change the Diesel Fuel filter….since there is all ways water in diesel fuel, gas…condensation…makes water…goes through the complete fuel system, weather it’s Diesel or Gas…
    Hope this will get people to get more life out of there Vehicles,

    1. Thanks so much for the comments. You’re right, all too often, just simple regular maintenance goes forgotten. Especially on a common rail Cummins (2003-current), fuel filters are imperative. Personally, I feel the best option is to replace it every 3,000 miles as its cheap insurance. But the best option is to swap out to something such as a FASS Titanium that will deliver consistent, impurity free fuel. This is the best insurance policy you can get for safeguarding the fuel system against failure.

  66. 2006 3500 with 24 valv3 5.9l engine 150,000 miles had hard starting issues. would start only when plugged in inside of heated shop..Grid heater light on but grid heater would get hot. Dealership diagnosed injector failure. Purchased and installed injectors. Truck now starts quickly but runs rough. Has a loud pinking sound. Produces copious amounts of white/grey smoke. tried to isolate sound to one particular cylinder by sequentially disconnecting injector wires but did not pin sound down. When installing injectors I torqued injector hold downs and feed tube nuts as per reccomended specs. Should I have torqued feed tubes higher than the specified 37ft-lbs? Am going to shop to measure injector bypass.
    Thanks very much for any help. You explain things very well

    1. Based upon your description, the issue is definitely fueling related. Presuming the truck received the correct injectors (Bosch part number would be 0986435505), and not mistakenly ones for say a 2003 – early 2004 (Bosch part number 0986435503), there are a few things this could most likely be. First, we’d recommend checking the valves and ensuring they are properly adjusted. Secondly, ensuring the connector tubes were properly seated into the injector bodies as described in this writeup. In many instances, if you torque the injectors down first, then thread the tubes in and torque those, the tubes are not sitting squarely. You also should have replaced the tubes when you replaced the injectors as again, many times the original tubes will have a seating ring at the tip from the original injectors that doesn’t seat the same in the new ones, leaving a gap fuel can bypass. Lastly, if you happened to pinch one of the injector wire during re-assembly. This doesn’t sound to be the issue since the sound didn’t change when you disconnected the individual harnesses, but still a possibility. These would be the first things to check, we wish you luck in getting your truck back on the road again running properly.

  67. I read your page on a cummins no start and was wondering if you can help me out. I have a 04 5.9 and it’s been hard starting, I changed out my fuel filter “which looked awful” and it seemed like after I did that I’m getting a rough idle surge. Surging just enough to be able to see it on the tack but my truck it straight piped and you can definitely hear the surges while I’m at a stop light or whatever. Truck does not surge until it’s been running for a little bit. Please help! Thanks

    1. Surging issues typically come down to an issue with the FCA, especially with a really bad fuel filter, contaminants can get into the actuator and cause issues such as this. The only thing that stops me from thinking it is the FCA would be the fact you stated about it happening after the engine was running for a bit. With that being said, I would recommend check the pressure relief valve. That can cause a surging issue as well. I would check that of course when you’re experiencing the issue.

  68. With the PRV removed, should you be able to blow any kind of air psi through it to see if it’s stuck open?

    1. Not that I am aware of. Most of the time they are opening too early, not completely open, under no pressure. If it is opening early affecting starting (starting psi is 5-7K) you will not be able to provide that type of pressure to that valve to check it with any pressurized air. Knowing that starting pressure is 5-7K, if it is leaking during cranking, its bad. No need to confirm anything past that as it should not be open at all.

      1. So lift pump and high psi common rail pump was replaced by another shop. They couldn’t figure it out so it got towed to our shop. After going through your check list posted up above, I found the PRV was stuck open, with the line off and cranking engine over, it would let fuel through. Take PRV out and I could blow through it. So got a bolt and put in place to block off, and still no start. Truck all of a sudden just died originally on customer.. Previous shop said high psi pump failed so that’s why both where replaced.

        1. Will the computer not allow the truck to start if it reads low oil psi? What is the minimal oil psi required for the engine to start?

        2. Thanks for the inquiry. Yes, based upon the fact that fuel was blowing past the PRV, it needed to be replaced or blocked off anyways. Since replacing everything, has the fuel system been completely primed to eliminate ALL air out of the system? Are there any codes? While this definitely sounds like a fuel related issue, its possible that one or more injectors need to be replaced. While not as common as a “slow death,” the injector(s) can fail to the point of the truck dying. When this happens, they’ve been on their way out for a while, but the owner / driver basically is slowly getting used to the harder starts and lower power over time, so when they finally give up, it seems unexpected. If this is the case, you’d be able to test the return rate of the injectors, which should be no more than 90mL per minute when cranking at 200RPM’s. If you’re in excess of this, time for new injectors.

          Regarding your question about oil pressure, you typically would have a check engine light due to low oil pressure. And if anything, the truck would start, but then die after due to a lack of oil pressure.

  69. I am a little confused. You are saying to measure return flow from the line running from the back of the head and Alldata to says to run the same test from the banjo bolt on the back of the filter. Which is correct?

    1. Both methods will work. We recommended using the one on the back of the head to make sure that you are isolating the injectors only. As far as I remember the injector return will not go back to the filter canister. Regardless, you just want to make sure you are measuring injectors only. If you pull the wrong line at the canister, your reading will not be accurate as there are other parts that return to the canister, as well.

      1. Thank You Josh. I have 300 ml return in 15-30 seconds cranking. ouch! Oh well, the injectors have 430,000 miles on them!

        1. Well, I’d say you got your money’s worth out of the originals then. Its never fun having to bite the bullet and replace injectors, but you’ve definitely got quite a few more miles than most at least. I don’t recall which exact year your 5.9 is, but here’s a couple injector offerings we’d recommend, genuine Bosch remans (remanufactured by Bosch, not someone else), as well as the upgraded connector tubes you’ll want to replace at the same time:


  70. What an informative website. Learned a lot by just reading over everyone’s issues and your reply to them with answers and suggestions. Great site . My 05 cummins has 329k on it now . Thank you and Aloha!

  71. Great information. I have a 2004.5 that towing up a hill, my truck acts as if it is running out of fuel about half way up the hill. I can get out of the accelerator and limp up the hill and is good to go down the other side and on the level. Any ideas.


    1. Thank you for checking out our blog! With the incline of a hill, there could be something in the pickup of the tank that is cracked or broken. Fuel will move to the rear of the tank possibly causing a loss of suction of fuel. The first thing I would do would be to install a fuel pressure gauge on the supply fuel line for the injection pump. I would monitor this while the issue is occurring to see if pressure drops when pulling a grade. If pressure drops, I would then look possibly upgrading your fuel lift pump and inspecting the pickup assembly in the tank for any issues.

  72. Thanks for the response. I can attach a gauge to my filter cap or do I need to try and pick up the pressure at the injection pump.

    1. You can certainly install the gauge at that location. I mentioned at the injection pump as that is where it really matters. Either location will allow you to see a pressure drop if that is occurring.

  73. 2006 cummins 5.9 started when cold ran fine started making a load grinding sound in motortemp was27deg itook to the shop he took off lines to the injection pump cranked truck no noise grinding . truck wont start what could be the problem

    1. This would be a tough one to determine over an email. Any grinding noise would be cause for concern. Were any codes pulled on the truck? Without hearing the noise personally, it’s very difficult to determine what it could be. Typically grinding noises would not be associated with fuel lines going to the injection pump. I would suggest pulling the valve cover on the truck to check valve lash, draining the oil to see if any metal is present, and possibly pulling the front cover to see if there is anything out of the ordinary there. If you’ve got any additional insight, please let us know so we can help get your truck running properly again.

  74. 04 3500 Diesel Quad Dually- 134,000 miles. Engine running fine 30 MPH, then suddenly all dash board gauges died. Drove home approx. 1 mile. Shut off engine. Turned on ignition, engine started a few seconds then shutoff. Fuse?

    1. This sounds like an instrument cluster failure as I’m not recalling there being an independent fuse for the cluster itself. Further, guessing you have one of the grey keys that contains a SKIM module / chip for theft prevention. When this chip itself either fails or basically cannot communicate with the ignition and cluster, the truck will start for about three seconds, then shut itself off. However, even if you don’t have the grey key, if the ECM cannot communicate with the dash cluster, it would cause the issue you’re experiencing.

  75. I have a 2003 3500 diesel 5.9 with lift pump upgraded from dealer to in-tank setup. I have a no start problem. If I plug the trucks block heater in it will fire after excessive cranking usually only after first removing cap off fuel filter housing and reinstalling. I’ve done all the tests above except the Injector bypassing in the return line test. I have a 8 codes that do not want to clear. Once I get it running it runs great. Idles smooth. Very responsive. It will start with a slightly longer crank time for the remainder of the day but overnight it goes back to a no start condition. Codes are 2607 (already replaced bad air heater relay and heater is getting warm now) 0251 (what will cause injection pump fuel valve feed back? Can this be my problem) 0113 ( not sure what is the cause of the intake air sensor high) 0514 (don’t think batt temp sensor performance will affect my no start) 0483( cooling fan speed shouldn’t be the problem) 0521 (oil pressure sensor performance, looks like I may have a bad oil pressure sensor but again shouldn’t cause a no start?) 0193 (fuel pressure sensor high, could this bee it? To much fuel pressure? Bad sensor?) 0480 ( again think this is unrelated but also confused why this won’t clear as cooling fan seems to be functioning just fine). I’ve disconnected batteries for over an hour and codes haven’t left. Could the no start be simply just a faulty fuel pressure sensor? If it was a bad cp3, FCA, or bypassing injectors, would I not notice performance issues or rough idling once it was running? Another thing I noticed last time I got it running Is that after shutting it off (after driving or just idling in the driveway for a bit) and re-starting again. It will fire right up if I skip the wait to start and turn the key straight to cranking. If I wait for the intake heater indicator to go out, it cranks a little longer than it should but still starts in a reasonable crank time. Next morning I go out and back to feeling like I’m going to burn out the starter or kill the batteries before it will start and like I said before, only if the block heater is plugged in and I play with the fuel filter housing cap will it Eventually start. Also have installed two new fuel filters and a new fuel filter housing cap as I thought it just wasn’t seating correctly and I was sucking air in past the o-ring. ( should also mention I ran the truck dangerously low on fuel a month before this began happening. thought I may have burnt out the lift pump but when doing the backyard fuel pressure test with a hose over the fuel line feeding the cp3 I have lots of fuel gushing out) I’m going to pick up a code reader to see if that will clear the codes and see which ones come back.

    1. First thing first, there are a lot of codes. Getting a scan tool and seeing if you can properly clear the codes and see what comes back would be a start. If everything fuel related such as lift pump flow, pressure relief valve, and injector return flow has been verified good, then you would need to start diagnosing each individual code that stays active. The codes are pointing us in multiple directions that makes it hard to isolate a single issue especially over an email. I also assume you have done a load test on the batteries as well? That said, it does have us leaning towards fuel related, especially the fact that this issue started with running the truck low on fuel. On one hand, as injectors are failing with these trucks, the warmer the cylinders are, the easier it will be to start the truck, and as they start to fail (obviously not completely failed), the truck will run just fine once its warmed up, but will be hard to fire, or at least crank substantially longer than normal. On the other hand, its also acting like there could be air in the system, possibly stemming from the in-tank fuel pump. Overall, you’re on the right path to completely clear the codes out and see what initially returns, then we an help diagnose from there.

  76. Firstly, thanks for all this free and helpful information! I have a 2003 2500 with 215,000 miles. Last week I started it as normal (it was cold, below freezing) and drove about 2 minutes, then it died like I had cut the key off. It has not started since. I have checked the batteries, they are relatively new and test good under load. The starter is spinning the engine at the normal RPMs to start. I have changed the fuel filter, checked the lift pump with a pressure gauge. It reads exactly 9 PSI while the pump is running. I have unplugged the FCA and the rail pressure sensor and tried to start it. No luck. Today I received a fuel rail pressure gauge that hooks up electrically to the rail pressure sending unit. When I attempted to start the engine, the intake heater worked as normal, the rail pressure went up to almost 2000 pounds, but then dropped to zero pretty rapidly while the starter motor was still engaged. I then took the top banjo bolt off the pressure relief valve and attempted again. I was hoping that it had stuck open, an easy fix. But no fuel came out the top where I had removed the line. I’m now thinking that my CP3 has given up. Is this the most likely scenario? I have not done the fuel return volume test, because I can’t see that one injector could cause pressure to read zero. Am I on the right track? Would a bad rail pressure sensor cause a “no start” condition? Thanks for your advice. I will post back once I find and fix the problem.

  77. Firstly, thanks for all this free and helpful information! I have a 2003 2500 with 215,000 miles. The injectors were replaced about 50,000 miles ago. Last week I started it as normal (it was cold, below freezing) and drove about 2 minutes, then it died like I had cut the key off. It has not started since. I have checked the batteries, they are relatively new and test good under load. The only code that was set was the camshaft position sensor. I reset the code. The starter is spinning the engine at the normal RPMs to start. I have changed the fuel filter, checked the lift pump with a pressure gauge. It reads exactly 9 PSI while the pump is running. I have unplugged the FCA and the rail pressure sensor and tried to start it. No luck. Today I received a fuel rail pressure gauge that hooks up electrically to the rail pressure sending unit. When I attempted to start the engine, the intake heater worked as normal, the rail pressure went up to almost 2000 pounds, but then dropped to zero pretty rapidly while the starter motor was still engaged. I then took the top banjo bolt off the pressure relief valve and attempted again. I was hoping that it had stuck open, an easy fix. But no fuel came out the top where I had removed the line. I’m now thinking that my CP3 has given up. Is this the most likely scenario? I have not done the fuel return volume test, because I can’t see that one injector could cause pressure to read zero. Am I on the right track? Thanks for your advice. I will post back once I find and fix the problem.

    1. You’re welcome, and thanks for the response. Okay, just to make sure, it sounds like you unplugged both the FCA and the Fuel Rail Pressure Sensor at the same time. If that’s correct, you need to leave the rail pressure sensor plugged in and only unplug the FCA, then try to start. If it starts, shut it off immediately and replace the FCA. Otherwise, unfortunately, based upon your description, it does sound like a dead CP3. If that’s the case, we’d recommend going with a genuine Bosch reman, such as this one that we carry:


      Hope this helps and if you have any other questions, please let us know.

    2. Hi there! Based upon your description, it sounds like your prognosis is correct, that its time for a CP3. Since the truck was running fine and then literally just stopped working driving down the road, that pretty much rules out injectors as they tend to take their time dying. The only other question is the lift pump. While 9psi is good, you need to make sure that it doesn’t just drop off after some time running. We’ve seen a handful of times that the lift pump will give the same issue (dies just driving down the road) due to insufficient fueling to the CP3, but that upon initial test, the lift pump pressure was good, but then falls on its face. Just make sure that when you’re testing the CP3 as you mentioned, that the lift pump pressure isn’t falling at the same time, which could potentially mean its a lift pump issue. Overall, I’d say you’re most likely needing a new CP3, though. I would recommend going with a genuine Bosch reman as a replacement, such as this one we offer: https://www.dieselpowerproducts.com/p-4991-bosch-cp3-common-rail-injection-pump-03-07-59l-dodge-cummins.aspx

  78. Recently had my injectors rebuilt on my 03 Dodge Ram. Truck started and ran great first week. Second week noticed longer crank time to start. Third we it would not start. Shot a little either intake go it started. Lift pump comes on and is pumping fuel. Replace FCA. No change. Could this be the CP3 finally giving out. Truck has 250K on it.


    1. Hi there, thanks for the question, but sorry to hear about your truck. In my experience, that would not be the CP3 because the truck would not continue to run once the ether “wore off.” Honestly, because of the fact that the truck ran after the injectors were rebuilt, then slowly went back to its old ways, it sounds like its still an injector issue. It takes a highly reputable injector remanufacturing facility to properly rebuild common rail injectors, such as yours. I would recommend performing an injector return rate test to confirm the return rate. That said, there is a chance the issue is derived from a failed pressure relief valve. “In theory,” if it was already on the ragged edge, then you added freshly rebuilt injectors that flowed more efficiently than the original injectors, now the higher pressure was the last nail in the coffin for the PRV. At that point, as you’re trying to start the truck its returning excessive fuel. The only part about that which doesn’t align perfectly with your symptoms is that it’ll start with ether, but there’s a chance. Run the test as described for the PRV just to rule that out. Good luck.

  79. 2011 Ram 2500 6.9l Cummins having starting issue. THe shift illuminator lights were all green, except Park which was red. The next day they are all out. THe security light is flashing like crazy on the dash. Have a key, not the fab so maybe that is why the flashing? But biggest problem is the truck wont start. It has power but doesnt do anything, wont even crank..but there is a click bear the fuse box. Have tested relays and all are good. Battery tested and was good. Took starter in to be tested and they said it was bad so I purchased a new one Installe dand still not starting Next step is to check the grounds once I can locate a diagram
    Any other suggestions or do you think the lights on the gear illuminator, security light flashing and no start could be related?

    1. This really sounds more like an issue with the SKIM key (chip in key) than anything else. Depending on which key configuration you have, you’ll have a chip in the key, or in the key with integrated fob. This chip serves as a sort of security device that if the vehicle computer doesn’t “sense” the chip, it will not allow the truck to start. If you have another key, I would recommend trying that first and foremost. Otherwise, the dealer can reset the key, but if memory serves me correct, they would also need to have the vehicle in their possession, as well.

  80. I have a 2007 Dodge Ram 2500 5.9l Diesel showing the p2146 and p2149 codes. The injector gasket has been replaced as well as the male plugs. I have ohm tested the injectors and they appear to be good as well. The main harness was also closely inspected and did not see any broken wiring. Both Batteries have been tested and one is new they are good. Grounds are good. New fuel filters and FASS pump are working. Any experience dealing with this?

    1. Hi there, and sorry for the issues you’re having, but sounds like you’re covering most of the bases in diagnosing the issue. The first question is whether you have a chip on the truck that plugs into the injector harnesses, such as an Edge Juice with Attitude. This is the most common situation that a fault will occur in either the connections of the aftermarket chip or within the module itself causing those codes. If you are, then I’d recommend disconnecting the chip, returning factory connectors to their original location, clearing the codes, and seeing if they come back. If you don’t, then your next best bet would be to trace the wiring back to the ECM pins and check if there’s any issues there (corrosion, open wire, etc.). Hope this helps, please let us know if you have any other questions.

  81. Hey Josh, I have a ’99 cummins that was progressively getting harder and harder to start. Started out just being hard to start cold then graduated to hard starts all the time. Had a code fly for crank sensor failure, replaced that the starter all the battery cables, new batteries, replaced all the return line o-rings etc. Now it starts like a dream as long as it’s warm. Can sit for up to 4 or 5 hours and will pop right off. Sits overnight and it’s a no-show… no-go. Takes three or four full cycles of the FASS lift pump to get it to fire. I’ve looked for a pressure relief block off but everything lists 2003 to 2007 years. Will this work on a 1999. Not sure why they keep showing these years since everything is pretty much the same right?

    PS: Local diesel shop defaulted to saying the Injector pump needed replaced. Thing runs like a raped ape the injector pump seems fine but they say there is a pressure relief valve in the pump that’s bad and if I disconnect the lift pump when cold starting and if the truck fires right off that’s what the problem is… It didn’t fire when I did that.

    Thanks in advance

    1. Hey there, thanks for the question and reading the blog. First things first, correct, your VP44 (your injection pump) truck’s fuel system is vastly different than that found in a 2003-2007. Technically, many of the same philosophies still exist, but the parts are very different and MUCH higher pressure in a common rail system, as found in the 2003 through current model year. That said, I’ve had two VP trucks (both 2001’s) and really like them. Anyways, the VP44 does have an overflow valve similar to the P-Pumps(its external at the return line). On occasion, those can become bad and cause a similar issue as to what a bad pressure relief valve does on a common rail Cummins. The simplest way to think about it is like trying to blow up a balloon with a hole in it…..you’ll never create adequate pressure because air (or fuel in this case) is always able to escape, and because these valves are controlled by springs, they will gradually get weaker over time. I would also be concerned about the amount of damage already done to the pump if air has been introduced to the pump (presuming the valve is bleeding off, which allows air to enter the system). No injection pump likes air as fuel is the source of lubrication. This could also be pop pressure on the injectors is off, but in most cases, these injectors are relatively bulletproof in comparison to the common rails, but still plausible based upon your symptoms. I’m not sure what the return flow for a VP44 is, but maybe run a comparison on how much fuel returns when the truck is running good vs. not starting. If its a drastic difference, it may just be the overflow valve. And lastly….since your truck is a 1999, up until 1999, from the factory these trucks had a metal fuel filter canister which is known to leak. If you’ve got a bad enough leak, again, air will get into the system, and the longer it sits, the more air will get in there, and make it very hard to start. Hope some of this steers you in a direction, and good luck. If you’ve got any other questions, please let us know.

  82. 2003 3500. Cranking no start. We have checked everything in the fuel system, injectors lift pump, all tests. Looks like a cp3 replace. But I have a question. If I take off the line from the cp3 to the common rail and turn the engine over how much fuel and pressure should be coming out of the line.

    1. Hi there and sorry you’re having trouble with your Cummins. The pressure coming out of the CP3 at start up should be between 5,000 and 7,000 psi in order to fire the engine, so we wouldn’t recommend removing the line and cranking unless you have a way to properly cap off the pump and monitor pressure. If you haven’t done so already, check your Fuel Control Actuator on the CP3 as discussed in this article. Otherwise, you may be correct in that its time for a new pump. When its determined it is indeed a CP3, we’d recommend a genuine Bosch for most applications, as shown here: https://www.dieselpowerproducts.com/p-4991-bosch-cp3-common-rail-injection-pump-03-07-59l-dodge-cummins.aspx

  83. 2004 Dodge ram 2500 5.9 24v bought truck with motor disassembled in bed, had another note put into it with new ECM programmed with Vin # of truck, had it running, drove down road up to about 30-35 mph started rumbling and sounding like rod knock with both white and black smoke coming out of exhaust until I shut truck off, start it back up ran normal til I hit the mph again, took motor out and put another motor in and now it won’t run, seems like electrical issue with code p2509 on again, also tested 6v going through ECM to FCA plugin, seems like it needs 12v through there for it to run? Any suggestions?

    1. Phew, sounds like you’ve got one heck of a project at hand, sorry for the troubles. Okay, in terms of what was going on with the first engine, there could be several things, such as if the cam was not properly timed to the crank, fuel delivery issues, fuel return restriction, or the valves WAY out of adjustment. The white and black smoke obviously indicates an overfueling versus intake air issue. As far as getting the second engine up and running, first things first, you need to load test both batteries and verify you’ve got good grounds. The ECM needs a full nine volts just to power up the ECM, let alone cranking the engine over. As far as the voltage at the FCA, six volts is normal, you’ll never have a full 12 volts there. Good luck, and let us know how things progress.

  84. Diesel Josh, Does the return fuel from the CP3 pump and the return fuel off of the back of the head come together at the fuel filter housing? I’m not sure I’m getting the return off of the back of the head isolated so I can measure it correctly.

    1. Hi there. The return for the fuel rail and the CP3 are tied together by the fuel filter canister. The injectors will have its own return that will return to the tank. With the valve cover off, you should be able to reach your hand back there and feel for the correct line and follow it down to its connection.

  85. Hi. I have a 2002 Dodge 2500 24 valve diesel. The truck has 310,000 miles but runs like a monster – until it doesn’t. The last 2 months it has 3 times died or refused to start because of – I think – a fuel issue. Another time it took three times turning the engine over to get it to start and then it idled rough for maybe 15 second before running the rest of the day being turned on and off repeatedly. That time was odd because the truck always starts up immediately. I’d say it might need batteries except for the 2 times it just stopped running after going fine for miles. The last time it was pulling a trailer in 92 degree heat when it just went silent – no cough, no sputter no nothing. Just 60mph one second and no fuel supply the next second. The guys who went to tow it said it started when they got there. Right now it’s at my place not starting. It ran fine until I parked it. So here’s my question: about the same time it started the fuel issue I noticed the engine temp guage on the dashboard acting up. The guage will not rise at all for maybe an hour even with the outdoor temp in the 90″s. It often does not register for longer than an hour. It will go up to halfway after awhile if I’m pulling something in hot weather. Could the thermostat not registering be tied to the truck not starting/dying? I live in a mega rural area and mechanics are few and far between. Each so far has had a diff theory. Thanks much and apologies for the long email. ~Valerie~

    1. Hi there, sorry to hear about your troubles. Its not surprising that you’re getting differing theories because the source of the issues could be one of several things, or honestly a combination. However, based upon your description, especially the part about the ambient air temperature and the engine temp gauge not reading, brings up something we’ve seen/heard of on a very rare occasion, and its a failed Engine Coolant Temperature Sensor. Your ECM uses data from the ECT Sensor to determine many factors, including injection timing, and if it fails, can cause exactly what you’re describing. We’re guessing some of the other theories revolved around a failing VP44 injection pump, mostly the electronics on the pump. This is still probable and we’d suggest checking for any codes, and if P0216 is present, you are definitely due for a new pump. It would also be a good idea to check lift pump pressure and volume at the pump. You should see 56 oz. of bubble free fuel feeding the injection pump in one key cycle if memory serves me correctly. These are suggestions based upon what could typically cause one of these particular trucks to have issues, but again, based upon your gauge and the temperature, our bet is on the Engine Coolant Temperature Sensor. Good luck, and please let us know if you’ve got any other questions.

  86. Hi again. Thank you for the note back. The truck is in the shop and at closing the mechanics were still unsure what is going on so first thing in the morning I will stop by with your theories of what might be the cause. In case it sheds further light on the matter, thanks to previous discussions on your site I got the idea of using ether to start the truck. So after 2 days of refusing to start 2 shots of ether and the truck started. It ran 33 miles to town, and once at the shop re-started five times. The mechanics said it is starting today as well. Does the truck starting with ether change your opinion?
    Anyway, thank you again ands yes – I will let you know the final outcome. Best ~Valerie~

    1. You’re welcome. Well, very likely it does cause a change in the theory as typically the need for ether is due to a lack of fuel. Without knowing the history of the lift and injection pumps, with this new information, I’d recommend first testing the health of the lift pump. This involves more than merely ensuring it has power and is pumping, more so HOW MUCH its pumping as its very common also for these pumps to pump and prime intermittently. If the VP44 injection pump does not have adequate fuel pressure, it will just die, similar to what you’ve described. Obviously, this doesn’t cure your issue of the gauge not working, which would be a separate issue. So, as I stated before, due to the high failure rate of the lift and injection pumps, lets start with checking their full operation, then you might also want to change the temperature sensor to fix the other issue.

  87. Hello again.
    The ECT sensor was replaced and the truck dash gauge still is not showing an engine temp reading much of the time. It must be a bad thermostat and thus not associated with the truck stalling/dying?
    The truck has run fine for two days since I got it back with the replaced ECT sensor but the not starting/dying issue must not be fixed since the ECT sensor was replaced and the truck still is not showing the engine temp.

    The one thing I didn’t mention so far is one of the earlier mechanics asking me if I had recently run the truck out of diesel. No- never below 1/4 tank and yes, the gauge works. Well, he said when he was troubleshooting he found a good amount of air in the fuel lines. He said he bled the lines and checked them for pressure/leaks and could find nothing. He did not drop the tank to check the seal or the fuel line in the tank.
    He said I may have a crack in the fuel tank line that’s letting air in or there may be a cracked tank seal and to keep the truck above 3/4 full to see if a fuller tank solves the problem.
    So I filled the tank – next AM it would not start. Gave it a squirt of ether- ran fine all day being turned on and off (with a full tank). That day it went into the shop for the ECT sensor.
    While it was in the shop for the ECT it got a rebuilt stearing gear box – the other was leaking pretty badly.
    With air in the fuel lines would you say testing the lift pump and checking for cracks in the tank seal/line are the best next steps?
    Either that or IV ether next to the air filter (not).
    Again, thank you.

    1. Its really starting to look like you have two separate issues – one with the temperature and one with the hard start/stalling. Yes, I would recommend having lift pump pressure first and foremost checked. The best idea here would be to install a mechanical gauge and literally zip tie it to your windshield wiper and drive around for a bit to check fluctuation. The pressure ideally shouldn’t drop below 5psi even under hard throttle. The next best bet would be to check the injection pump, but unfortunately, the only good way to test that is to remove it from the vehicle and have a pump shop test it, unless there’s a P0216 check engine light, then its definitely in need of replacement. Hopefully its just a lift pump, though. Air in the lines can typically be entered into the system due to “bleed back” of the fuel system, whether the lift pump can’t maintain pressure, or the injection pump, or even the injectors themselves, and if the injectors are still original with over 300k on the odometer, they’re also likely in need of replacing. First and foremost, check lift pump pressure while DRIVING, not just a quick idle test.

  88. My Son took my truck to work but did not notice that there was a bad oil leak from the engine as he departed. He drove about 6 miles before noticing the truck slow down power and got engine light for low oil. he parked in a dollar General parking lot. I had the truck towed to home checked the oil and there was just about a 1/8 to 1/4 ” of oill on the stick. The leak came from an aftermarket oil filter that loosened up (but why no oil on the ground when parked?). I do not know how after driving the truck and parking it for a couple days with no leakages noted that when he goes to drive it that morning it leaks like all get out!
    Well we replaced the lost oil and changed all the filters to which I did not note an excess of metal in the oil or not burnt smell. The engine can be rotated but will not start. I have had it sitting for about 6 months due to hectic work schedule right now. but need to trouble shoot. I am hoping he did not burn up my Cummins!

    1. Okay, first things first, there’s nothing in the ECM that would be preventing the engine from starting/running if oil pressure is lost, it will just run until it dies. There’s a possibility that once it lost oil pressure it toasted the rings and now the engine does not have enough compression to start, but it can turn over. In terms of why there are no oil leaks when its sitting, that should simply be due to no pressure pushing the oil out of the faulty seal on the oil filter. If you crank the engine over and open the oil cap, you should be able to feel an excessive amount of air coming from the opening. First thing I’d recommend is to check for any check engine lights and see if that points things in a certain direction.

  89. I have a 2003 dodge 5.9 cummins. It will not start without a dose of ether. I am building 7,000 psi plus rail pressure while cranking. After a squirt of ether it will start and run fine . any ideas?

    1. Hi there, and sorry for the issues you’re having with the truck. Sounds like you’re building adequate rail pressure, so that’s a good thing. The downside is it sounds like you are in need of replacing the injectors. I would recommend to have an injector return rate flow test performed to confirm this. If that is the issue, then you’ll want to replace all six along with new connector tubes. If you’re not looking to increase the power output, I’d recommend genuine Bosch remans along with the updated Bosch connector tubes, shown below:


  90. Jonathan l Shoemaker4444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444 says:

    I have a 2007 dodge 2500 with the 6.7 cummins while driving it shut off i found the return line on the injector pump pushed off fixed it and truck has not started back up i have the fass system on it it is working

    1. The first thing to do would be to bleed the air out of the fuel system. In order to do this, you’ll need to crack all six injector lines at the head and “bump” the key to engage the lift pump. Once you get fuel bubbling out of the first line, close/tighten that line. Then, continue to bump the key and close off lines until you get at least to line #5, then close the remaining. At that point, you should have most of the air out of the fuel system and can start the truck unless something else failed when the line came off, but more than likely, its just air in the system.

  91. Hi
    I have a 2004 dodge 2500 with the 6.7 cummins while driving it shut off. When key on, lift pump is working. it wont start, fuel is coming utill high pressure pump. Unplug FCA, wont start, Removed the supply line from high pressure pump to common rail, no fuel . PLease help me.

    1. Hi there, thanks for the question. The first thing to verify is that you have a 2004 model year with a 5.9, as you stated you had a 6.7, and not that you maybe have a 2007.5+ with a 6.7, but either way, the same principles will apply as they’re very similar systems overall. Based upon your description, its most likely one of two things. First, you mention you have fuel at the injection pump, but the question is whether you have sufficient fuel, so you’ll want to run the bucket test described in this tutorial to confirm you’re getting enough. I’ve seen plenty of times that the pump is “working” but not optimally feeding the CP3. Next, if absolutely nothing changes when you unplug the FCA, then more than likely its a CP3, especially if you have absolutely nothing getting to the rail. You’d be surprised at how little it seems actually is getting to the rail for the engine to run properly. We’ve had numerous people tell us they’re not getting “anything” to the rail, when in fact its adequate and merely a bad pressure relief valve is causing the issue, so I’d recommend also pulling the return line off the top of that and visually checking for fuel, again, as described in this writeup. Good luck, hope any of this helps and you get your truck up and running.

  92. 04.5 5.9 no-start. I am getting 6.3V to lift pump circuit and to FCA connector as soon as key is switched to run. 6.3V will remain until key is turned off. Cranks but no start. Problem started when loose, passenger side battery terminals disconnected while running over train tracks. Suspecting ECM but looking for advice. Thanks.

    1. I would be concerned about the overall battery voltage itself especially if you’re already having issues with the cables falling off. If its coming in less than 9 volts during cranking, the truck will not start. Doing a load test would be recommended. If the ECM has failed, I would try to read the ECM with a scan tool. Typically you would get a communication error with a scan tool when trying to read it if it has in fact failed.

  93. Thanks for the reply. I am doing this for a customer. I did correct the battery wiring and both batteries tested good. I was suspecting the ecm because the 6.3V I measure at lift pump and fuel control actuator on the cp3 does not seem right. I thought the fca would either get 12V or nothing and the lift pump gets the low voltage as soon as key is switched to on and does not cut out prior to cranking. It just stays at 6.3V. I have checked power supply and grounds at ecm, as well as pin 32 for ign, power from key, though not while cranking. Customer replaced ecm a year ago due to bad alternator providing too high a voltage. This damaged cluster, first ecm and who knows what else.

  94. Forgot to mention my scanner can talk to all the modules except ecm, tcm and abs. With known good batteries, voltage to lift pumps and fca increased to 7.4V during crank.

    1. If you’re not able to communicate with the ECM, and just for fun have a battery box hooked to the batteries, and you get no communication from the ECM, then more than likely its another ECM. To verify, you could perform a pin out test, as well. There is also a fusible link before the ECM you could check to confirm power. See these two schematics for reference:


  95. I’ve got an 03 2500 24v 5.9, 129k miles. It has a slightly hard start from cold, depending on temperature. It starts normally if very cold. If the truck has been running long enough to heat the cp3, say 30-60 minutes, and it is then turned off, it becomes no start until the cp3 cools back down.

    Pouring half a gallon of room temp water on the cp3 when hot enables it to start.

    Unplugging the fca when no start does not enable it to start.

    It is throwing code p0251.

    No misfiring or stuttering. Does feel weaker than my 05 24v, and gets worse mileage (19.1 vs 25.1 according to onboard).

    What is the next test to pinpoint the issue? Should I suspect the fca if unplugging it does not enable start? Could it be the lift pump causing the cp3 to overheat? Could it be an injector at only 129k miles?

    1. Hi Marc, thanks for the question and taking the time to read our post. First and foremost, P0251 means “Injection Pump Fuel Metering Control ‘A’ Malfunction.” Basically, its just saying that the CP3 isn’t getting the commanded pressure, which could be a few different causes. The easiest one is to check/replace your fuel filter. If this is clogged, obviously will lead to an unsatisfactory fuel pressure to the injection pump. Next up would be to check your lift pump pressure. For this, I wouldn’t recommend merely hooking up the gauge, starting the truck, verifying pressure, then saying “good enough.” I’d get it hooked up, make sure you’re running at least 8psi, then drive the truck with the gauge zip tied to your windshield wiper so you can watch what’s happening as you’re driving. More than likely, the CP3 is getting hot because its not getting sufficient fuel to cool it down. And then the truck isn’t running…because its not getting sufficient fuel for combustion. Regarding your question about the FCA, if it doesn’t fire off when its unplugged, I’d say no, but not for sure. The FCA is literally just a metering valve, so when they fail, it usually is metering excessively, hence not allowing the pump to build pressure. But once unplugged, it tells the pump to run wide open. So, if no change when unplugged, that’s usually not the culprit. Overall, start with fuel filter, then move onto lift pump, and let us know what happens after that.

  96. 2005 Dodge 3500…died coming down 95 south Mystic Ct…..towing 25 ft. boat….got towed home…changed fuel filter …no start…cranked …and cranked ….also filled filter bowl….nothing !!…..Should it at least fired with bowl filled ?….Replaced filter before ….and it started right up….Lift pump ? any info would help now….really don’t want to go in shop at their billings….truck only has 136000 + …..never had any problems with my 1992 Dodge !ST gen…..for 26 years….PLEASE HELP …..L.T Elliott in CONN

    1. Ooopphhh….there could be a lot of things going on here, but lets presume its fuel related. I personally would go out on a limb and say its likely the fuel pump or possibly the fuel control actuator on the CP3 based upon the fact that the truck just died out of nowhere. When injectors, PRV, and other fuel related items go out, its a longer death, but your truck just simply died. Because your CP3 isn’t strong enough to support fueling on its own, if the lift pump dies, then the truck will shut down. And the same goes for the FCA. I’d recommend following the guide on this blog to verify if those are working. First, unplug the FCA and see if the truck fires. If it does, then replace the FCA. Then, test the lift pump to see if its pushing any fuel. Your truck has the in-tank pump presuming its still the factory and hasn’t been upgraded. I’m leaning towards fuel pump personally. Try these things and get back to us with the results. Good luck!

  97. I want to start off by apologizing for such a long email.

    I have read a couple of your blogs and was hoping you could steer me in the right direction


    July 14, 2016
    June 24, 2019

    I have a 2005 RV with a Freightliner XC chassis.

    It has a Cummins 5.9l ISB-300. The ESN is 57274714. The Service Model Name is ISB CM850. The Engine Dataplate states that the Build Date was October 14, 2004.

    The Cummins has a Bosch 0445020015 CP3 / Common Rail fuel injection pump.

    This RV has 66,789.2 miles on it.

    On my last trip, when going down the ramp to merge onto the interstate, it seemed to have what appeared to be a slight engine miss. This happened on two different occasions, both times when entering the interstate. It ran fine once up to speed. I didn’t notice anything traveling on a two way highway.

    The other day I had driven the RV and parked it in my pole building. I went out about a month later to go top off the fuel tank. I turned the key on and waited on the “Wait to Start” light to turn off. When it shut off, I cranked the engine over and it fired up. It cranked over normally, but it only ran for about 5 seconds and shutoff. I tried starting it again with no luck. It cranks over fine, but it just won’t fire.

    I read an article stating that weak batteries could cause this. Mine seemed to be fine, but they were dated, so I replaced them. I replaced the cranking batteries with those having 1000CCA each. Still no start.

    I checked my water and fuel separator and it was dry. This was strange. I read an article about a hidden fitter that could cause the problem. So, I replaced the Racor 025-RAC-10A in-line filter, which is found in the frame rail just behind the right rear wheel. I also replaced my Fleetguard FS19596 water and fuel separator.

    After this I started checking the lift pump.

    The lift/transfer pump seems to run okay. I pulled the fuel supply line from the CP3 pump and measured the fuel output for 60 seconds. I got roughly 96 ounces in 60 seconds. That equates to about 498 milliliters in 10 seconds. This seemed to be ok.

    I didn’t have a pressure sensor and gauge, so I installed one right before the fuel enters the Fuel Control Actuator and I am getting around 9.5-10 PSI before cranking.

    And to top off the “no start” issue, the radiator got a leak and drained out the coolant. So now I also have a “Low Coolant” indicator. And of course this is a diesel pusher and I back it up to the wall in my pole building. So, I need to be able to start it to turn in around to be able to work on the radiator.

    I tried replacing the pressure relief valve with a plug, but that didn’t work. Still no start.

    A local mechanic connected his scanner to the ECM and everything appears to be ok. He did say that when cranking the engine over, that there wasn’t any oil pressure. But it has been setting for a few months.

    He suggested replacing the FCA. So I replaced it, but still no start. I then unplugged the FCA and still no start.

    I have been told that the CP3 pump is almost bulletproof. And with the RV only having 66,789.2 miles on it, I am hoping that this is not the problem. When the mechanic was checking the ECM with the scanner, I asked his opinion about the CP# pump being bad. He said that since the engine started and ran for around 5 seconds, that if the pump went bad, I would have heard some knocking or clanking.

    Any help at this point would be greatly appreciated!!

    Thank you in advance for any advice you provide!

    1. Sounds like you’ve done a very thorough set of tests, which helps, as well as your explanation. If we look at this as being a fuel related issue, the only thing you have not checked would be the injectors. I would check the injector return rates at the back of the head. I am not sure if they have the same return line setup in motorhomes as they do in pickups so keep that in mind. Regardless it should be at the back of the head. Maximum allowable leakage for all injectors is 40 ml per 10 seconds at 200 RPM cranking speed for engines with a no start condition. Injectors can return too much fuel without throwing any sort of fault codes. This will give you an idea if any of the injectors are not adequately fueling the engine. You could also run an ohm test on each injector harness. You would need to isolate the harness from the injector, then ideally you will be less than 0.05 ohms of resistance. You are right that the CP3 “should” be fine with the amount of miles that are on it, but that being said, most motorhomes do have a tendency to sit quite a bit, so if you picked up a bad batch of fuel, you could merely be either dealing with bad fuel, or bad fuel that also contaminated the CP3 and/or the injectors. I’ve personally picked up two bad batches of fuel that caused no start issues, requiring the tank to be dropped and fuel replaced. In one instance, the fuel station had filled the diesel tank with unleaded, and in another situation, had excessive water.

  98. Hi Josh,

    I don’t seem to be able to use the reply function on this page, but this is a response to the comment you made on August 4th to my original question.

    I checked the filter as you suggested and it was absolutely caked with crap. I replaced it with new and the hard/no start seemed fixed. Over the last 2 weeks, however, the same issue has creeped back up, culminating in a total no start from cold last night.

    It had been taking progressively more water and/or longer waits to get the truck started after being driven any longer than about 20 minutes. However, now it is quite cold here, and I’m not sure if the problem is the same one, or just difficulty because of the temp (around 26-30f at night now).

    I’ve had a pressure test kit sitting in the back of my truck for weeks, just waiting for the time to use it, looks like I waited too long now that it won’t start.

    It does turn over, albiet somewhat slowly. Further, I can hear the lift pump cycle when the key is bumped. Would it be diagnostic to open the fuel filter drain and measure how much is expelled when cycling the pump?

    Mine has the block mounted lift pump fwiw.

    1. Marc, first, I’d recommend checking the fuel filter again. If its caked again, then you may have bad fuel that needs to be addressed. I’ve never tried to open the fuel filter drain and bump the key. In theory, that would work, but I could see the issue of opening it and bumping the key at near the same time to avoid the filter canister filling with air if the pump doesn’t kick on soon enough. The preferred method is described in this post, but specifically:

      “remove the fuel supply line before it connects to the injection pump and place the open end into a bucket under the truck. Next, hop in your truck, and “bump” the key. When I say bump the key, just turn the key to crank the engine for a second in order to engage the pump. At this point, you should hear the pump run the duration of its cycle. For reference, the 2003-2004.5 trucks came equipped with a block mounted lift pump and the 2005-2007 trucks came from the factory with an in-tank lift pump, yet many of the 2003-2004.5 trucks were later retrofitted with this same in-tank design. This will give you a gauge on where to listen for the “hum” of the electric motor on the pump. Once you’ve bumped the key, presuming the pump is operating normally, you should see fuel dumping into the bucket.”

      I’m still leaning at a failing lift pump causing your issue, please try and follow that procedure to diagnose the truck and let us know what you find.

  99. Josh,

    I did the lift pump end of the day two days ago. Seemed to be starting normally that evening. Next morning after 20 degree overnight temps was no start. Had a small emergency, so used a gas soaked rag to start it. Drove it maybe 1 hour, ran fine, parked it at home. Sat for a couple of hours, then took two tries to start. Drove it for an hour and a half straight, parked it for 45 mins, then couldn’t get it started. Had to dump a bunch of water on it again, then got it going. Took it home, parked it overnight.

    This morning took two tries and then got it running. Drove it around for an hour and a half, came home, changed the fuel filter. The one I just put in last month was dirty, although not caked like the last. Let it sit for two hours, then couldn’t get it started. Was forced to do the gas rag trick again. Drove it 2 hours straight, parked went in a store for maybe 30-45 minutes, came out and it started right up. Drove two blocks, parked for 15 mins, couldn’t get it started.

    When it runs it runs fine, no stuttering, it’s getting better mileage than it was before (24.6 vs 19.1 last month), seems to have plenty of power. Seems like it wouldn’t be the injectors or cp3??

    You mentioned bad fuel… I’m wondering if previous owner (who was in rural Nebraska) might have had some bad diesel. On top of that, I drove it through Canada and had to fill up at some podunk stations, so I may have had some bad fuel as well. I’m guessing you are thinking the in-tank module’s filter could be clogged with crap? I will probably have time to put the pressure gauge on it tomorrow to see what the pressures are like with the new pump. If low, would you suspect dirty tank/filter? How would you confirm that, besides dropping the tank?

    Assuming it isn’t the high pressure pump or the injectors, then the only other thing left would be the prv, right? How do you diagnose that? I’ve read that the return line will have fuel in it whether the prv is faulty or not.

    1. Marc, when you say that you “did the lift pump,” do you mean that you replaced the lift pump? Regarding your question about the Pressure Relief Valve (PRV), testing that is also described in the blog, but in short, you’ll remove the return line and start the truck. If fuel is bleeding past the PRV (or potentially blowing past it with high pressure, so watch out!), then its failed. An inexpensive fix for that is to merely install a pressure relief valve block off. Have you tested the injectors? Have you checked lift pump pressure while driving? Have you removed the plug to the FCA on the CP3 to see if the truck starts with it unplugged?

  100. Hey, thanks for the article. My 03′ 5.9 started with an erratic idle, jumping up and down a couple hundred RPMs. No codes, but then Live data showed the rail pressure jumping 7200psi-3600-5400psi at idle. I replaced my FCA, and later also had to replace my Fan clutch. My truck is stock, 170,000 miles. I started troubleshooting for a leaking injector, I tested Lift pump supply, CP3 return, and injector return, all were within spec but injector return was a little high. I then started capping off each injector one at a time. When I got to cyl #3, the truck shut off, just after I noticed rail pressure fluctuation looked better. I thought maybe I’d run out of diesel, so I put a couple gallons in but the truck never started again. I re-checked lift pump supply, still good.

    I bought enough caps to cap the rail off, and I need to mention I also checked the Relief valve and Pressure Sensor, but the rail will not build more than ~120psi now capped off. I even did the 30 second CP3 crank test, and it delivered enough fuel. At this point, I’m at a loss, and ready to send it off to a Diesel mechanic. The only thing I can figure is the CP3 pump just happened to fail at that moment. I’ve tried unplugging the FCA and FAN, swapping the Pressure sensor, it doesn’t build past 120psi cranking with good batterys.

    1. You’re welcome, and thanks for reading it and the question, but sorry to hear of the issues. First, do you know the actual return rate specs of the injectors? You mentioned that the injector return was a little high, but what exactly was it? The only way I would think that the truck would shut off after capping cylinder 3 would be if you capped off the only injector that was not returning too much fuel. CP3’s can fail, 120 PSI is wayyyy to low obviously, so its either a massive internal leak in the high pressure system, or a bad pump assuming the supply fuel is in spec. The only test you did not mention was testing the injector wiring harness and the solenoids on the injectors. That however would not explain the low rail pressure to begin with. This is all sounding like a bad CP3, presuming everything was tested properly.

  101. Thanks Josh for the reply. I’m leaning toward a bad CP3 as well, even with only 170,000 miles, the last fuel filter was in there way to long, AND the truck wasn’t driven much from 2012 – 2018. The injector return might have been around 150-180ml, I’d have to look for notes. I was capping off one injector at a time and looking for a drop in fuel return and High Fuel pressure stability. I had a mechanic tell me that I might have blown the reed valves in the CP3 by capping the whole rail off after it wouldn’t start anymore. But I’m planning on replacing all the injectors and connector tubes. Also dreading the news that the CP3 is bad.

    1. No problem, Tony, hope you’re able to get to the bottom of this. As far as the injector return spec, for a truck that will NOT start, should be about 40mL per ten seconds of cranking. If you only capped the relief valve on the rail, that shouldn’t have caused any issue, but if you capped off all of the injectors at once or just the overall ability to feed from the pump to the injectors, then yes, it would have more than likely taken out the CP3. We’ve got a bunch of options on replacing the injectors and pump if it comes down to it.

      Pump: https://www.dieselpowerproducts.com/bosch-cp3-injection-pump-03-07-cummins
      Injectors: https://www.dieselpowerproducts.com/bosch-stock-503-injector-03-04-cummins
      Connector Tubes (original style): https://www.dieselpowerproducts.com/bosch-f00rj01572-connector-tube
      Connector Tubes (new style): https://www.dieselpowerproducts.com/bosch-connector-tubes-03-18-cummins

      Pump: https://www.dieselpowerproducts.com/p-bd-cp3-common-rail-injection-pump-03-07-59l-dodge-cummins-stock-exchange
      Injectors: https://www.dieselpowerproducts.com/p-bd-premium-stock-replacement-503-common-rail-injector-03-04-59l-dodge-cummins

      Injectors: https://www.dieselpowerproducts.com/dynomite-diesel-50hp-injectors-cummins

      Injectors: https://www.dieselpowerproducts.com/p-15410-industrial-injection-0986435503se-iis-reman-stock-injector-03-04-59l-dodge-cummins.aspx

  102. HELP i just bought a 2003 dodge ram 2500 common rail 5.9l not even 24hrs of owning the truck it was -30 outside i got in the truck got the glow plug going 3times truck started right away and 1min later died by itsefl not it cranks and wont start , bring the truck to the dealership told me my cp3 pump was out so i bought a new cp3 and truck still crank but wont start 3000$ later truck wont start…

    1. Hey, Justin, lets see if we can help to figure this one out. Now, did you install the pump, or did they? If they did, pretty surprising that they let you head out the door and the truck won’t start. If they only diagnosed the pump as bad, then you installed a pump, did you bleed the air out of the system by cracking the injector lines, bumping the key until fuel comes out each line, then closing off each line? Did you check the fuel filter? That’s the first place that when fuel gels it accumulates into a slimy blob (that’s the technical term!). From there, I would start at the lift pump and work my way up. Verify the lift pump is supplying the proper amount of fuel as presented in this article, then remove the return line from the Pressure Relief Valve on the fuel rail and see if its leaking out of the PRV, also as described. If those are good to go, then you’ll want to check the injector return rates to see if they’re actually the culprit. Let us know what happens on any of these and we can go from there. GOOD LUCK!

  103. Hey Josh, update on my earlier post regarding the ’03 5.9l 24v No start’, the shop indeed isolated it to the CP3, it’s running again! Much quieter now, I’m happy with that. The only problem now is that the original issues from months ago has returned. Randomly after I start the truck, or when I come to a light, the RPM’s jump like I tapped the gas pedal. It’s bad when it happens at a light, because the truck wants to jump forward. It’s only done it once after the CP3 was replaced, but the second thing is the fuel pressure. Set point is aprox 5400psi, and watching L.D. for a minute or so at idle, actual jumps from 5400 – 6900 – 3600 back and forth. Any ideas? Thanks.

    1. Tony, well the good news is PART of it is fixed! Now, lets see if we can get to the bottom of the other issues. My first question would be if, when it lurches forward, are you seeing this rail pressure spike (6900) you’re mentioning, or is that random? If you see the spike when it lurches, did you end up putting the stock pressure relief valve back on the rail or is it still capped off? If its the stock one, I’m wondering if that’s in need of being replaced. Next, when the CP3 was replaced, I’m presuming the CP3 included a new fuel control actuator (FCA, also called an MPROP sometimes). This controls / meters the CP3 by being given values from the ECM.Without an FCA, the pump runs at max pressure, and if its failed/failing, will cause sporadic pressures. Next, if your injectors have a high return rate, that can also cause fluctuations in rail pressure, have you tested the return rate across all six? Okay, lets start with that. Now, if the rail pressure isn’t associated with the lurching, the lurching could be caused by a bad torque converter also (as well as other things), but hoping the two issues are associated with one another.

  104. Hey Josh, I’ve driven the truck a bit more, and it honestly runs smooth. The lurching didn’t happen this time, but watching the live data, yeah the pressure still bounces from 6900 – 3600 – 5400 back and forth. I’m wondering if the pressure sensor is failing. The relief valve was replaced by the shop, and the FCA may have come with the pump, but if it’s the old one, I bought it about a year ago and it was a Bosch. I haven’t attempted any return testing after the shop got it running, I didn’t want to undo any of their great work. But would like to pinpoint these last few issues. For the injectors, #1 is new, the rest have 170,000 miles on them and are original from 2003. The shop did mention the return looked good though. Thanks for all the advise!

    1. Tony, sorry for the late response, your question unintentionally got buried! I would look at commanded versus actual rail pressure. Commanded is going to be what the ECM is telling the pressure to be whereas the actual will be what is being read at the rail. Excessive injector return rates can affect rail pressure. I would get the spec from the dealer on what the return rate was when they checked it. Five original injectors with 170K on them, I bet some of those are not within spec as far as return.

  105. Hi i just bought a 2003 common rail 2003 cummins it was -30 truck was plug in i have any gel in the tank and a webasto heater, in the morning i hop in the truck it started for 1min and stalled by itself after that truck cranks but wont start so i took of the fuel filter everything is good in there after that i took the fuel line out of the cp3 ans i have no fuel comming out so i took the line going in the cp3 and bumped the key i have fuel coming out there , so i brought the truck at the dodge dealer and they changed my cp3 pump said it was not working so now i have fusel coming out of the cp3 but it is not a big flow ,capped one injector at a time truck still cranks no start,blocked of the prv still crank no start truck dosent have any codes i did the key cycle 3-4times no error code im desperate in finding what it has ,have you ever seen that before ?
    trcuk has 5” strait exhaust ,custom 80hp tune,built trans ,stock injectors and stock pump

    1. Hi there, sorry for the troubles, especially on a “new-to-you” truck, that’s never fun. Okay, so you mentioned capping off the injectors to try and isolate the issue. When you did that, did you measure the return rate that should be measured while capping each injector? For a no start like what you’re dealing with, it should be no more than 40mL per 10 seconds of crank time. To fully diagnose this, we’d would suggest starting from the beginning of the test and then get a baseline injector return rate, and then start capping off each injector to see if the return rate goes down with any of them capped. If it does, then you know that at least the one injector is in need of being replaced. But, unless the injectors have been recently replaced, its best practice to replace all of them, including the connector tubes, at once. I do have to wonder, though, the fact that the CP3 was replaced and still not starting. Did it run when you brought it home, and just not starting again now? Or did you tow it home and it was mis-diagnosed?

  106. Hi Josh,i bought the truck and it was running very good but it was the next day when i got in the truck i started it,then went inside my house to let it warm up i went and i heard the truck stalled by itself , so i got back in the truck to start it again and it just cranks but wont start so i tried to diagnose it myself , first thing i took of my fuel filter to see if the fuel was geled up , after that i got the banjo fitting of the cp3 the inlet one and had fuel there ,so after that i took the banjo fitting of the line going out of the cp3 and had just a little bit of fuel coming out so i got it towed to my local dodge dealer,they called me the next morning and told me they did some test and turned out it was a bad cp3 , so i bought a new one from my local parts store since the one at dodge was 3500$cad and the one i bought was 1100$ i brought the pump to them ,they put it in and the truck still cranks but wont start , they are now doing a bunch of test they told me they block off the prv and it still wont start,after that they cap one injectors at a time and it still cranks no start,they called me today and they think the new cp3 i brought them have a default from manifature in it im now at 18hrs in labour 110$ an hour and truck still cranks but wont start…

    1. Justin, did you or the dealer do a low fuel pressure test yet? For a bit of backstory since this truck is new to you, the 2003-2004 model years from the factory still had a low pressure fuel pump mounted in the engine bay, to the fuel filter to be exact. In 2005, they updated the trucks to an in-tank lift pump and started superseding the original design and retrofitting trucks to the in-tank design. So the first question would be where is your lift pump and is it still original? Has anyone does a low fuel pressure test yet? I know you said you have fuel coming into the CP3, but its a matter of how much, because if there’s not adequate fuel volume and pressure (at least 8 psi sustained), the truck won’t even fire, whether it has a new CP3 or not.

  107. Very good information, but specific to my issue. I have an early built 2003 dodge 2500 with a starting issue. This fall it was taking a longer crank time to start, but it started and ran fine. This winter it failed to start. Plugged in the block heater and the truck started with a long crank time and ran fine. Did some testing and found out my intake heater did not have power and traced it back to the solenoids. Replaced both and verified the the heater was working again. This did not fix problem. After some research, I found out there is a fuel heater on the fuel filter, but I cannot find out any information on testing or function. The truck only has 87,000 miles and sits for months at a time. Fuel filter was changed ~4,0000 miles ago. Any help would be greatly appreciated.

    1. Hi there, Rick and thanks for the question. In regards specifically to your question, I found some good information in a forum that aligns with how we’d know to test the fuel heater, shown at the below link.


      The other concern for me is the length of time the truck sits and whether you may have a significant amount of water in your fuel due to condensation. When you change your fuel filter, do you also drain the water separator located at the base of the fuel filter canister (yellow tab)? When you do get it started, is there any sign of white smoke or rough idle? Are you able to store it, at least temporarily for a night, in a heated shop or garage to see how it starts then? If so, this would also conclude its a condition of temperature.

  108. Thank you for the information. I do not have a heated garage to put the truck in, but I am also waiting till the weather warms to work on it. As far as draining the water separator when I change the filter, I open the valve but no water ever comes out. I am very careful to always park the truck with a full tank and I normally use a fuel additive each fill up. I will do some testing when the weather warms and let you the results. Again thanks.

    1. Rick, for when you’re able to work on the truck again, something to think about: when you open that valve, its draining ANYTHING in that bowl, and there “should” be fuel in there. The idea is that first water will come out, and then fuel. So, if you’re not getting anything out of there, you have one of two issues: 1.) the valve isn’t working/properly opening 2.) you’re not getting any fuel into the bowl. If its the latter, remove the cap on top of the canister, removing the fuel filter out, and make sure its full of fuel. You may have an issue getting prime, which 95% of the time will be due to the lift pump not working.

  109. Hi diesel josh , they finaly resolve my non start issue on my 2003 common rail 5.9 24v the first cp3 pump i bought was a rebuild from autoline and had a default from factory and wasnt building the proper fuel pressure to start so i boight the oem one from dodge and now my truck runs top notch
    Thanks for the info and now i have a PO700 code on the key cycle so i will get that scan tomorow

    1. Now, that’s frustrating when you diagnose something, replace it, still have the issue so you’re scrambling to figure out what else could cause the issue, only to figure out it was still the original part you replaced! At the end of the day, glad you were able to get the truck up and running. On the P0700, that’s a transmission code, hopefully THAT ONE is a simple fix. Good luck, and let us know what it comes back with.

  110. Finally warmed up enough to work on my truck. Cleaned all battery connections to ensure good voltage. Had a buddy crank the engine while I checked voltage. Voltage from one battery positive to second battery negative during cranking was ~10 volts. Checked tachometer in truck was cranking at 200 rpm, did not start. Plugged in block heater for a couple of hours. Watched tach in truck cranked between 200 and 300 and the truck started after a few seconds of cranking. Thinking starter not cranking engine at sufficient rpm to start under cold conditions. Not sure if starter is just old ( 2003 truck ), or if there is a another problem in the starting circuit. Any help in testing to track down the issue would be greatly appreciated.

    1. Hey, Rick, glad you’re back at it. What I would do is determine whether its a lack of voltage versus cold starts versus a bad starter causing the issue. To help guide you in that direction, if it were me, I’d have the truck’s block heater plugged in and just go try to start it, see what happens. Then, presuming it was a hard start or no start still, grab another vehicle and run charging cables between both vehicles’ batteries, and try it again. Was it any better? Without removing the alternator and starter to have them tested, this will at least give an indication as to whether its the starter or a charging issue. If it the truck started easier, then you can safely presume its a charging issue and need to check the batteries and alternator. At your recorded 10 volts during cranking, that’s pretty normal, what was it like once it was idling? Was it around 13.5-14.3 or so? Should be. If the truck started the same with hooked to the other vehicle, then you can guess its probably a starter. On the other end, though, I’ve personally had independent issues where my block heater and grid heater had failed. For the grid heater, as long as you have power at the leads when the dash is indicating the heater is on, then that should be fine. For the block heater, while I’ve never tried this, in theory, you should be able to remove the heater from the block (screws into passenger side), ground it, and apply power and see if its getting hot.

  111. 06 5.9 start and runs great when engine starts to come up to temp motor starts lunging and eventually dies will restart after long crank or let it set and will restart as normal. previous shop replaced injectors, cp3 and lift pump. i have replaced the rail pressure sensor due to throwing code with no changes

    1. The first thing I would recommend checking is the pressure relief valve. You can either go through the sequence as described in this article, or you could also install a pressure relief block off, such as this one, which will completely eliminate the possibility of excessive fuel rail pressure being bypassed:


      If that checks out, I would have an injector return rate test done on the injectors. I realize that the shop just installed new ones, but without knowing what they are (how good they are), could be a culprit, or if the injector connector tubes weren’t properly seated into the new injectors.

  112. Hey there, was pleased to find this page still comments years later. Anyway i have an 04 5.9, i just did an in frame overhaul. I had broken rings on #1 and #6. Truck still ran and started without hesitation, just down on power ect. Anyways, So i got it back together and am experiencing a crank no start. I unplugged the fuel rail pressure sensor and it fired up but ran poorly, idles for a bit and eventually shut down. During the rebuild i make shift hot tanked my fuel rail parts to clean them and i left the FPS and the PRV on there thinking they would be fine. Is there a chance that i caused the sensor to malfunction due to the chemicals and boiling water? I havent had a chance to see if the bypass valve is leaking by. But the truck will start, with that sensor unplugged and the FCA still plugged in, or both unplugged. But as soon as i plug the fuel rail sensor back in the truck immediately dies. Truck is currently at my old house and i live an hour from there but trying to diagnose and hopefully fix the issue when i get back out there. Also i don’t own a scanner to help diagnose to see rail pressure etc.. any input id appreciate, thankyou for the time

    1. Hey there, Chadwick, thanks for taking the time to read the article and the question. Based upon what you’re describing, I would definitely replace the rail pressure sensor as it is likely it could have gotten damaged. The PRV is a simple mechanical valve, so I can’t see how that would have gotten damaged, but likely the electrical sensor. Also, since the truck starts with the FCA plugged in, that’s likely not the issue. Its probably throwing some “whacky” values at the ECM when you plug in the rail sensor so its just not sure what to do, or sends a very low value and it cuts down CP3 pressure, killing the truck. Here’s a genuine Bosch replacement that we have in stock currently to swap out, truly thinking that’s the issue:


  113. I have a 2005 5.9 and it’s only running on the second bank. I’ve tested the injectors and they all omd out good, I’ve checked my power coming out of the computer and it seems fine. Is there any other test I can try?

    1. Have you tested the injector harness(es) itself? You would also need to ohm test the wires as you did for the injectors, but make sure you disconnect from both ends, then it will be looking for the same 0.5 ohms or less of resistance. We’ve seen quite a few harnesses fail causing a similar issue.

  114. I have a 07 6.7 I changed the lift pump and sensor on back of cp3. It ran good for the weekend and was headed to work when it just died out of nowhere. I got it home and changed the cp3 pump it’s a brand new Bosch. Still won’t start unless you give it a shot of either then it runs good unless you let it get under 2000 rpm’s. Any suggestions would be greatly appreciated

    1. This sounds most like an issue with the pressure relief valve. The lift pump runs a static pressure out of the pump and does not increase or decrease pressure with RPM, so what it sounds like what’s going on is at low RPM when the CP3 itself isn’t pushing additional pressure, its blowing prematurely out of the relief valve until you reach enough pressure out of the CP3 to overcome that. If you follow the instructions outlined in the article to remove the return hose and verify you don’t have any fuel coming out of the top of the valve at idle or start up. If you do, then you need to either replace the pressure relief valve with a new one or replace it with a relief valve block off. I’d recommend a new valve. If that checks out fine, I’d test the fuel pressure of the lift pump. Being you have a 2007, you’d have the in-tank pump unless you converted to a frame rail mount or some other aftermarket pump. Even with the new pump, its possible there’s an issue with the pickup assembly. Same theory, its sucking enough air to run poorly at low RPM’s, but then as RPM increases, it overcomes it. Its still much more likely to have an issue with the relief valve and where I’d recommend starting. Let us know how it goes!

  115. 2004 5.9l dodge Ram replace batteries and cables and now truck crank but won’t start not getting power to the ecm , all gauges on instrument panel are dead and got no power to hook up my scanner check all fuses all good , connectors all good any help will be very much appreciated

    1. Have you tested the voltage from both of the batteries? I’m presuming this issue only started after replacing both batteries and cables. Have you made absolutely certain that all connections are to the right spot? And yes, I know this question may seem obvious, but did you remove the plastic caps from the battery posts?

  116. First, you folks deserve the highest regards for this venue of help! In all my years, I haven’t seen any business provide a better medium for auto repair advice … for free or otherwise. THANK YOU!
    I have a 2005 Dodge Ram 3500, 5.9, 313,000 miles, AirDog fuel system.
    Have not had any issues with the truck in a long while. Drove to my brother’s last night and all was okay. Got ready to leave and when I turned the key, the usual lights and gauges came on; fuel pump running, etc. BUT, the starter solenoid makes loud click, or thud, but absolutely no movement (turning of the engine) otherwise. Static battery voltage of 12.75, Load voltage of 12.45, no codes show. There is a prominent “click” each time the key is turned, but no engine movement at all. The “click” IS the starter solenoid engaging, or at least trying to. Don’t know if the problem is the starter itself or could the engine be froze/locked (for whatever reason?). Like I said, I have not noticed any evidence of problems in advance. This just occurred (seemingly) all at once.
    Have you any ideas as to what the problem actually is and/or how to go about identifying it?

    1. Thank you for the good words! The good news is that its highly unlikely that the engine seized up all of a sudden, but to be certain, put a wrench on one of the damper bolts on the front of the engine and you should be able to turn it over by hand. That said, sounds more than likely you need a starter. One other thing, when you say you’re load testing the batteries, are you actually disconnecting them from one another, or just checking voltage while cranking? I want to make sure that one battery isn’t trying to compensate for the other and the system is unable to engage the starting solenoid. Last thing, those trucks can get corrosion in the battery cables, so at the very least check them over to make sure there’s not enough corrosion to prevent full power getting to the starter.

  117. I attempted to use the “Reply” link several times regarding my earlier post about my 2005 Dodge Ram not starting or even turning over, but keep getting an error message. Thank you for your reply. You got it right with the last tip! I checked the underside of the positive battery cables and found a good bit of corrosion. I removed and cleaned all battery terminals and whatdoyaknow?! Old dolly cranked right up. Also, thanks for the tip about load checks. I was simply checking the voltage of both batteries from the “primary” battery. Before cleaning the terminals I checked the voltage at the starter while the key was held on and the voltage was dismal. It is amazing how much current can be lost to corrosion.
    Said it before, saying it again: You guys are awesome.

    1. I’m sorry for the trouble you were having responding, Ron. That said, VERY glad you found the issue and got your ’05 up and running again. Where we’re at (Spokane, Washington) we deal with pretty considerable corrosion due to de-icer in the wintertime. When you’re ready for a future project, checkout these replacement battery cables we offer from Custom Battery Cables that include new lines, terminals, and everything is cut to length, ready to swap out. Its a pretty common issue, unfortunately.


  118. Wow, what a serious amount of information in one place!

    I might as well run through my question, a little different use case though.
    My Cummins ISBe 3.9 (C.Rail 24v) is in a Paccar Medium Duty 7.5 ton truck!
    I bought it with this fault. It has been stood for 3 years.

    – Starts everytime within a second or so, but a heavy diesel knock, slight under power, stable idle, bit of blue smoke and will rev to the govenor/limiter.

    – Engine warning light on – no scanner available (24volt system)
    – Full wiring from all sensors (Map/air/coolant/oil) to ECM resistance checked – no breaks/high impedance.
    – Injectors measured at EM plug per injector at 0.4/5ohm – too high? Engine running would seem not.
    – Checked head return trickling on idle – more on higher rpm (need to repeat with scaled container and timer)
    – Measured fuel pressure in Volts rather than pressure, only 2.3-2.4v on idle, does not change no matter what
    engine rpm.
    – Checked PRV – fuel pouring out – blocked this off completely. Started engine – FP now maxed sensor out at
    4.5v and is really diesel knocking loudly.
    – unplug FCV – same condition (expected), suspected FCV stuck closed.
    – Used FCV from later 4.5litre Euro 5 engine, plugged in, will not start, unplugged max FP (4.5v)

    I think next steps are repeat leak offs now PRV/FCV are replaced/working.

    My other concern is potential FCV driver in the ECU is dead, when I test the circuit with a lamp the lamp is lit constantly, no pulsing of the PWM drive?

    It has no MAFS.

    Thanks in advance

    1. Mark, it sounds like you have a few different things going on, but I’d recommend starting with the worst offenses first and then going from there. In regards to the Pressure Relief Valve and the Fuel Control Actuator – Yes, based on what you’re saying, its running at max load and it was previously blowing right past the PRV but now that its blocked, its trying to run it all through the injectors. If when you unplug the FCA and have it plugged in, and you can’t tell any difference in how the engine is running, you most likely need to replace the FCA. In regards to your injectors, they’re considered “good” as long as they are measuring 0.5ohms or less, so you’re right on the edge there of needing to replace them. I’m betting the blue spoke is due to the FCA being stuck and showing excessive fuel into the cylinders, but you could also be dealing with at least one injector that is now damaged and delivering too much fuel as a result of the FCA. In terms of measuring your fuel pressure, I’d really recommend measuring that mechanically to get a better gauge on what your fuel pressure looks like as it will definitely fluctuate depending on engine load, but not necessarily RPM. Anyways, I’d start by replacing the FCA and see what changes after that. Technically, you could also have some wiring that’s chaffed or broken going to the FCA. I’d also recommend inspecting the wiring or also running an ohm test there, as well.

  119. Yes I have a 2006 Dodge ram 2500 with the 5.9l diesel and I am having some problems with it. When I first start it up when cold is skips real bad and puffs white smoke out of it. The exhaust smells like bug spray which I have been told that is raw fuel. I replaced the injectors and the CP3 pump but still does it. But after about 30 minutes it starts ideling fine and the smoke goes away. I am lost at this point can you please see if you can help me.

    1. Donald, yes what you’re experiencing is fuel that’s sitting in the piston bowl(s) that needs to be burnt out of the cylinder which takes some time once the truck is fired up from a cold start. The normal culprit for those would either by the injector(s) or the fuel control actuator on the injection pump, so it is surprising that those didn’t fix your issues. But since they didn’t, time to figure out the cause. When you replaced the injectors, did you also replace the connector tubes? As described in this article, if the tube doesn’t properly seat into the side of the injector, its a common place that can leak right into the cylinder. When installing new injectors, its important to tighten the tube a little, then the injector a little, then the tube, and so forth so the two “seat” properly into one another. Next, have you had the injector harness ohm tested as described, as well? 0.5 ohms or less are necessary. One more thing, have you had a compression test done on the truck just to be absolutely positive you’re not experiencing some blowby? Yes, that would normally be more of a blue smoke, just wanted to make sure that’s not it.

Your email address will not be published. Required fields are marked *