Tractorman

Is your part number 604018 (a Dorman part number)? From what I have read on-line, this blend door actuator motor is universal and should work on your truck. It seems that there should be a calibration procedure, but I cannot find one on-line. It might be worth a call to the manufacturer to see what they have to say. Another possibility is to find a used actuator motor from a salvage yard. John

Wow! I have to commend your perseverance to get as far as you have. Good description of your issue. I don't have much offer at the moment. I think you may be right in regarding a previous owner thinking there was a dash wiring problem. Electrical ground problems, back feeding problems, and short circuit problems can be some of the most challenging electrical issues to solve. I think I would put my first focus on finding what is causing the 15 amp park lighting circuit fuse to blow under certain circumstances. You find that, then maybe everything else will fall into place. Also, I would look for any evidence of other accessories (especially lighting) that may have been wired by a previous owner. Do you have a wiring diagram to work from? John

It will give you time to clear your mind and come up with a good diagnostic approach. Possible issues to keep in mind: intermittent fuel supply blockage, especially suction side of lift pump large amount of air in fuel system (not likely) intermittent power to lift pump faulty lift pump (pressure regulator issue) When things get difficult to diagnose for me, I change tactics and try to prove what is working CORRECTLY, not what is working INCORRECTLY - a process of elimination. This method will sometimes get the issue resolved sooner than focusing on things that one might think is wrong. John

Are you referring to the wiring connector to the blend door actuator that shows a three-wire connection? It looks like others have had the problem you are having. Have you confirmed that you really have a blend door motor actuator problem, or is it possible that the interposer (plastic shaft) is cracked and slipping on the old one? In that case, you can just replace with Heater Treater's steel interposer. You will have to reset the gears though. Heater Treater has a video how to get the gears timed. John

Give details of your bucket test. Have you ran the engine while drawing fuel from the bucket with a separate power source to the lift pump? I'm having a hard time with believing it to be a VP44 overflow valve problem. Did the FASS representative explain with detail on exactly how an VP44 overflow valve problem would adversely affect lift pump pressure? Also, if there is a restriction in the fuel supply anywhere in the lift pump circuit (especially the suction side), then unpredictable fuel pressure could be expected. What it the GPH rating on your lift pump? John

So, it sounds like the lift pump relay was not the issue? Symptoms remain the same? John

You could just disconnect the fuel pump relay to test a warm start condition. Rig up a jumper wire to hold in your hand while you start the truck - that way you can control when the lift pump runs (or doesn't run) for your test. At least, it would let you know if too high lift pump pressure is causing your long crank on a warm start. John

@Mopar1973Man, that would be you...., John

Does this mean NO slow start when the engine is cold? If so, your lift pump pressure may be too high. The OEM fuel pump setup uses PWM (pulse width modulation) to reduce supply voltage to the lift pump, thus reducing fuel pressure, while cranking. The reasoning is that high lift pump pressure during cranking can affect the position of the timing piston, thus making the engine hard to start when warm. Not everyone has experienced this, but some have. Is your relay wired directly from the battery? You could try reducing lift pump pressure to see if this helps starting a warm engine. Don't get caught up in the, "you gotta have at least 14 psi lift pump pressure", as it is not true. Take it down to 12 psi or so at idle and see if that helps. Good to hear you found the problem with the lift pump. John

On my truck the tee at the back of the head started to leak fuel about 15,000 miles ago (at 390,000 miles). At the time I had the transmission out while doing a clutch job and I noticed the leak. The connections were loose, so I just tightened the them from below. They have never leaked since. A leaking tee fitting (even if it's only leaking air) can cause long cranking times, but it will not affect fuel pressure after the engine is running - so, not likely to be your problem. I haven't tried accessing the tee fitting from the top of the engine. I would probably remove the valve cover and use a mirror to inspect the connections and then blindly reach around the back of the head to tighten them. John

The tech is probably referring to the 14 psi overflow valve in the VP44 injection pump. This pressure control valve is very reliable and I am almost certain it is not your problem. People have replaced this valve because of not understanding how the fuel system works, and then found after replacement, their symptoms didn't change. Even if the overflow valve failed (as in opening at a lower pressure), it would have little or no effect on lift pump pressure. All fuel that enters the VP44 must pass through in internal fixed displacement vane pump. This pump is regulated at 100 - 300 psi depending on engine rpm and engine load. Because the internal vane pump is fixed displacement, additional fuel cannot be forced through it regardless of lift pump pressure. Both Airdog and FASS lift pumps use a ball and spring check valve to regulate fuel pressure by recirculating any fuel that is not being used by the injectors and the VP44 cooling system. If the lift pumps are high volume pumps (which yours probably is), then a lot of fuel has to recirculate, in fact more fuel recirculates than gets used. The pressure control valves on these lift pumps are usually not of high quality and the ball and seat can take a beating, which can cause symptoms that you are experiencing. I am surprised that the Tech didn't mention this. I would be looking at two possibilities for low / erratic lift pump pressure. Check the condition of the ball, spring, and seat in the lift pump. Check for any restriction / leaks in the low pressure fuel supply. Pay special attention to the suction fuel lines from inside the fuel tank to the lift pump. Many people that have observed erratic lift pump pressure have stretched the spring in the lift pump's pressure regulating valve for a bit more tension. For some it gave desired results. John

From what I understand regarding engine break-in for Cummins, is to operate the engine at various engine rpm's and various engine loads for a specified number miles (not sure about the miles ), and to not use synthetic oil during the break-in period. What Cummins does not want is a steady engine rpm and a steady engine load. Not sure about the use of break-in oil. John

I think you would have found it. Your scanner was telling you that you had low voltage at the injection pump. I should have recommended that you check that connection as that connector is part of the battery supply voltage. You ought to hook your scanner and see if the voltage to the injection pump is now steady and higher than it was. That would help to confirm your find. John

A poor connection at Pin #7 would absolutely match your symptoms, as it is the 12 volt power supply from the fuel pump relay. Keep us posted - hoping you will never experience the issue again. John

I was using the FSM to figure out what your corroded wire operated. If I am looking at the diagram correctly, terminal #9 should be the culprit. This pin-out says #9 isn't used. Am I looking at the correct pin? Do you know the wire color? John

This is great news! Your perseverance has paid off. I think you have found the problem. And you did it without replacing a bunch of parts. Congratulations! Good job with repairing that connector. John

Had you noticed any driveline vibration or noise prior to the event? Had the driveline been removed and re-installed recently? Was the rear u-joint still in good operating condition disregarding the damage from the end yoke failure? In other words, were the end caps lubed, not dry? How do you use this truck? Does it do any sled pulling? burnouts? I only ask these questions just to cover anything that may generate shock loads to the drivetrain. Personally, I would just replace the parts needed with the OEM style end yoke. After seeing what happened with your truck, I think I will inspect the end yoke on my truck. - John

Looks like a U-bolt style was used on the 2nd generation 3500's, but not the 2500's. I think the U-joints are a 1410 series on a U-bolt style. A conversion would be possible, but probably costly. Did you do a failure analysis to determine whether it was an instant failure, or one that was coming on slowly? The photo doesn't show all of the broken area, so it is hard to tell if there was a crack first, then a breakaway. As far as I know, the OEM type end yoke is not problem connection. - John

Thanks for posting video. That is definitely all cylinders cutting out - like the fuel is briefly shut off intermittently. I watched your video a few times. Couple of questions. Just before the first cut out, your tach increased in RPM's. Was that you pressing the throttle or did that happen on its own? Can you make it happen? If so, exactly how do you make it happen? We gotta get this fixed! John

The concern is with his varying battery voltage at the injection pump (not the ECM), which has been demonstrated in his graph. The graph below his first graph. His most recent graph has improved, but is still unstable. Do you have the capability to produce a graph on your truck to show what battery voltage should like at the injection pump? John

I apologize for not getting back to you yesterday. I had some emergency roof repairs to do as a result of an overnight wind storm. I did try my scanner late in the day, but apparently my scanner is not capable of reading battery voltage at the fuel injection pump. @Mopar1973Man , can you perform this test on your truck? John

I think the wires that you are referring to are for the fuel heater and water-in-fuel sensor. You may set a code if they are disconnected, but I don't think it will affect driveability. I think you are on track with verifying good electrical connections between the battery, the ECM, and the PSG on the VP44. "Volt Drop" + "Injection Pump Battery Voltage" seems to equal 14.00 volts, give or take a couple of hundredths on your graph of over 800 reading covering a 10 minute span. On some readings where the voltage is low (10.9 for example) adding the "Volt Drop" doesn't bring it to the 14.00 volt value. This could be because there is a split second recording delay from one reading to the other. I have a scanner, but I don't know if it will display voltage at the injection pump. I will give it a test tomorrow. John

The 12 valve engine ('94-'98) uses a P7100 injection pump - no electronics. The Gen3 engine (starting in '03) uses a common rail fuel injection system. The only comparison engine that would work for you to test would be in a VP44 truck ('98.5-'02). If a single cylinder is misfiring, it would feel similar to a gasoline spark ignition six cylinder engine misfiring on a single cylinder - such as a spark plug misfiring. The misfire in your engine would feel stronger as more engine throttle and load were applied, whether or not it is a random cylinder or all cylinders. I suspect that it is all cylinders if it very jerky under power. The fuel solenoid inside a VP44 injection pump fires every cylinder, so if its electrical power source is temporarily interrupted, all cylinders will be affected until electrical power is restored. John

I have never done the type of testing that you are doing, so I don't any experience here. But, it would be good to see the same tests performed on a good running VP44 truck and compare the results. Is that possible for you to do? Is the bottom horizontal scale "time in milliseconds"? When the engine cuts out, does it feel like is a random cylinder misfiring, or does it feel like all injectors quit firing briefly? John

APPS (accelerator pedal position sensor) on the Cummins. When the APPS becomes output signal becomes intermittent as it ages, a specific code is usually set and the engine typically goes right to idle - referred to as "dead pedal". The dead pedal lasts for about 10 seconds or so, then goes back to normal until the next event. The photo below is from one of your earlier posts. I would be specifically concerned with re-checking the voltage to the injection pump. Voltage falling down to 9.5 volts could easily cause intermittent operation of the fuel solenoid valve in the injection pump resulting in random injection events not happening. This does match your symptoms. John John