Thunder2001

I just got my rebuilt ecm from Auto Computer Exchange and after reading bad reviews about every other company, including Them, I decided to take a chance. My experience with them was good, and I got a good Ecm back that was properly flashed for my truck. My problem is that I don't think my Ecm was bad to begin with, my truck still has the original problem.

There is a ground connection under the drivers side battery box. It has a bunch of ground lugs on it and seems to be a common trouble spot.

Still runs the same. This weekend I am going to go thru all of the grounds again to double check. I will also look at the APPS wires to make sure of no shorts and good continuity.

I am running out of parts to need swapping. I have replaced almost everything on it. The funny thing is is that it will probably be something simple. Just haven't had that a-ha moment yet.

Before all of this started I had a problem with the lights and the blower motor not working properly and it turned out to be a super corroded ground lug under the drivers side battery. I replaced the connections with new and it was fixed. I also had the alternator output wire rubbed through end have an intermittent short to ground on the alternator housing. I also repaired the wire and rerouted it further away from the housing. I replaced the alternator just in case. Could any of this have affected my PCM ? If so, could that contribute to my problem? Quite honestly I do not want to throw another part at it unless I have to. I will try playing with the ABS and VSS asap and report back.

Would the can bus data come from the ECM ? If so this is a fresh ecm and it is doing the same thing the last ecm did. Also would the PCM have anything to do with this? The PCM is one of the only original parts left on it. one more thing is that my harmonic balancer looks bad but I didn't think that it could cause this problem. Sorry about my poor typing skills, I am learning as I go.

The APPS is brand new and I did do the proper reset on it. Last time I checked, the tps numbers seemed to be moving smoothly along with pedal movement. Seems slow on the video because I think the scan gauge might have a slight delay when throttle is pushed.

Update 2/24/2017. Here is the video I said I was going to post. Let me know your thoughts.

Make sure your TV cable is adjusted properly. I had a problem with mine being sticky from corrosion. Lubed the cable till free and re adjusted and fixed my late lockup problem.

A slide hammer would get em out for sure. At least it would not put a sideways force on them. And just go easy with it.

I feel your pain on this problem, my truck is giving me the same type of trouble,only worse. I really think the pump hot wire test is only good for showing mechanical soundness at idle. With the ecm unhooked, you can't throttle up the motor to check for any type of misfire. What if there is some type of intermittent signal going to your VP 44 when it is hooked up. There is no way to test for this as far as I know. I was even thinking about making a connector to go between the VP connector an the VP to check for corresponding voltage changes in any of those connections.

Yes you are right about the pump, so I have made a relay and harness and am going to see if it helps. I am just waiting on my Big Line Kit and proper fuel pressure gauge to come from Vulcan. I just want to eliminate any possible problem before I run it again. I will be very disappointed if after all this, that it ends up being another faulty VP. I will report back as soon as I run it again. Well I have installed the Vulcan big line kit and the relay for the lift pump. I also installed a mechanical fuel pressure gauge. These changes made no difference in how it runs. I will post another video sometime today just to show you guys. The only thing left is maybe the waste gate is stuck open? Would that cause a stumble under load? I don't even want to drive it like this for fear of not making it back. Just an example of what happens, If I try to create a driving load by doing a small brake torque, it will just stumble till it dies. Also I did check for AC voltage and had a maximum of .012 volts. Running out of ideas and thinking maybe a second bad VP 44. Doug from BlueChip said sometimes the electrical parts are like light bulbs and they are bad out of the box. Maybe both these light bulbs came from the same box?

Yes you are right about the pump, so I have made a relay and harness and am going to see if it helps. I am just waiting on my Big Line Kit and proper fuel pressure gauge to come from Vulcan. I just want to eliminate any possible problem before I run it again. I will be very disappointed if after all this, that it ends up being another faulty VP. I will report back as soon as I run it again.

Thank you. I am gonna make one up asap.

Is the relay in your drawing a separate relay, or are those the numbers from the Relay box under the hood? I also have a pump made for stock location and Air Dog says to just plug and play. Maybe I will change it .

I do have a guy that has all the good scanners but would have to make an appointment. He is one of those techs guys with no mechanical skill. Kind of like the commercial where he can't fix it but he just tells you it is broke! Is the stock lift pump powered directly from the ECM? I looked at the wiring diagram and it shows the power side of the pump going straight to pin 35 and 15 of the ECM . I thought the ECM would control the fuel pump relay to then power up he lift pump. I could see this to be a problem especially if the Air Dog has a high draw.

Just came in from looking at it and ran it and watched the scan gauge. the scan gauge and few dash gauges were suprisingly both accurate. the tps reading seemed riight on with pedal position except in the display you could see small traces of a number1 flashing next to the number. Almost looks like it is supposed to do that. It is real cold out there today but I want to rig up a test fuel supply to rule out the lift pump completely. Doug at Blue Chip said it wouldn't hurt the VP as long as I didn't do it long. I shut the engine off and checked the APPS reading with the pedal movement and it goes from 0 to 99% smoothly.

Wow I really appreciate all of your help guys. As far as quitting, I am so deep now that It's got me pissed off now. I will not let it beat me. I wake up at 2 in the morning because I just thought of another idea. as far as the Alternater goes, that is a brand new remanufactured one that I had them test twice before I took it home. The banjo bolts are new but are the ported BD Diesel bolts that supposedly flow better. I am going to try and run it without the alternater hooked up to see if that helps. The Apps is also brand new and the lift pump is hook up to factory connection. Today I will try to note the symptoms a little more accurately with this scan gauge and report back. I was hoping that someone would have heard the noise and said oh yea I have heard that before it's your whatever. I guess this is just my luck but I have never had anything that has been this hard to diagnose. I have also tested the fuel tank venting and replaced the cap for safe measure. As far as a fuel restriction goes I would think that if you had one at the pump inlet it would show up in the clear fuel line test as cavitation bubbles.

194,000 miles on truck, owned it since new. Truck seems to run cleaner with new injectors, so it was probably about time to replace. I have no visible fuel leaks anywhere. I do have a shop fuel pressure gauge that I use to check fuel pressure and I have the pump adjusted to 20 psi at idle and it never goes below 10 psi on acceleration. Never have any starting problem, starts right up. This problem has pretty much stayed the same no matter what I have replaced. I just feel that it is something that I have missed. I guess it could be another bad Vp44, but I just want to make sure before I bother the guy again.

I have my fuel pressures set at 20 psi at idle rght now. I just went and picked up a scan gauge 2 and tried it and the MAP is reading 28.6 at idle and when I turn the engine off with key on it reads the same. does this sound normal? When I throttle it the motor almost sounds like it is hitting a rev limiter. It will just keep stumbling as I hold the throttle down.I just don't want to damage anything by doing this.

Yes it does the same things on the street,only worse. I really am afraid to drive it much. Everything is stock New blue chip Vp44 his best stock pump,air dog Raptor 100 Lift pump,brand new stock injectors and connector tubes,new cam sensor,map sensor,coolant sensor,re manufactured ecm, Beans Diesel sump and lines to lift pump,new overflow valve and all new Banjo .bolts and seals. that's all I can think of Right now but I am sure I will think of more. I took the engine wire harness off and totally stripped all the tape off and checked for continuity on each wire,there were no problems so I resealed the harness and reinstalled. The reason I did this is because the local Diesel shop told me that he thought the harness was bad. Cummins does not currently make or stock a harness for my truck and if they did It when update cost $1200.00. Logic tells me that the Vp44 to be bad wth the exact same symptoms would be pretty low. I just had the clear fuel line on between the lift pump and injections r pump and when it stumbles like that the fuel in the line shows no air at all.

motor stumbles when under slightest load. slow acceleration no problem. video attached explaining everything that has been replaced and tested