Mark Hodowanec

I have a 2004.5 2500. I was driving and the engine just died. The truck will not restart. The way it just died, it seems as if it has to be electronic.

I do not have a scanner, but when I checked the codes by turning the key three times p2121 came up.

The truck has been running well with the exception of periodically going thru some 'stuttering' which is consistent w/ a APPS failure. When it would stutter, I would also get a p2121 code which is also consistent with an APPS failure. It has not 'stuttered' for a month now and was not stuttering when it died. Also, I thought that when the APPS would go bad that the truck would run in limp home mode and be able to start.

Any suggestions on what to look for? I have worked on my vehicles in the past but am really backed up with a million of things and will probably have it taken in somewhere.

I am located in western PA (in Murrysville, just east of Pittsburgh). Can anyone recommend a good shop to take it to. I am reluctant to go to a dealer (unless someone has a strong recommendation).

Quick replies would be very much appreciated!

6spd05Dually

Mark,

Do you have any other p codes showing up besides the p2121? Let me know.

Mark Hodowanec

none other than p2121

Foxborough

I searched the site using P2121 and found this thread, It may help. Reply #5 caught my eye.
https://www.dieseltruckresource.com/...ighlight=P2121

6spd05Dually

That's good. Go look at the APPS sensor on the pedal. Check the wires that plug into the sensor to see if they're okay. I wouldn't remove the sensor from the pedal. They're electronically calibrated so removing it might destroy the calibration.

If the wires look okay, do you know how to measure resistance on circuits?

j_martin

I had a problem with my first gen TPS. Tried various cleaners and contact restorers on it with no success, till this one. Been 100% since. It's also good for any electrical connection.

DeOxit D5. Get it at a music/guitar store. They use it on their high powered electronics. Rat Shack has it in small quantity for an illegitimate price.

Odds are good grounds and/or connectors are the base problem.

Mark Hodowanec

Update. The shop I took it to suspects a bad lift pump. They say that there is no fuel pressure. I thought that the CP3 would have enough pressure to suck fuel at low load/idle. Is this not the case? If the fuel pump is bad can it damage the CP3?

Dodgezilla

Mark, these 3rd gens are designed to quit running if the LP stops working. That way it saves the CP3 from overheating and dying. I have read of some trucks continuing to run with dead LPs though. Hopefully yours is just one that worked as designed...

StealthDiesel

Whether the CP3 can pull fuel thru a dead lift pump and keep the engine still running depends on the lift pump.
When my original, stock, engine mounted lift pump died many years ago, the engine would not run at all.
There was no warning at all. My fuel pressure gauge went from 5PSI to 0PSI & I was stuck on the side of the road.

With the in-tank fuel pump or aftermarket lift pumps the CP3 may be able to pull fuel thru even if the lift pump is not working.
You would never know unless you had a fuel pressure gauge. This is why a fuel pressure gauge is so important.

BTW, if you don't have fuel pressure guage, a quick way to tell if your lift pump is working is to open the fuel filter cannister water drain.
Bump the engine to activate the lift pump. If the lift pump is working, fuel will really shoot out the water drain.

This is also a really easy way to drain the fuel tank.

6spd05Dually

Mark, I got busy that day and didn't get back on till now. Sorry about that. Did you resolve the issue yet? My truck is an 05 and there has been about 3 times driving down the road and it would just die. I had to let the truck sit for a bit and then the ole girl started right back up. These computer systems can be worse than a woman in how picky they are about things. I wouldn't go replacing the fuel pump without really knowing that's the exact cause. I have seen people just assume it's a lift pump over some code when that's not the case a lot of the times. Anyway, let us know.

turbochabot1

Any other codes from the shop that suspects the lift pump? APPS (TPS) failure is quite common but so is the filter mounted lift pump. Have you checked your fuel filter? Clogged filter could cause the symptoms you have with exception of P2121 code. I would suggest doing Voltage Drop test on the grounds, it is quite possible that a bad ground or corroded wire may be causing issues with ECM. A visual inspection and quick clean if any suspect grounds will not hurt either way. A fuel pressure guage would allow you to verify fuel pressure but I am assuming that the shop you bought it to checked this. StealthDiesels suggestion on bumping the starter with the filter drain open works well to see if lift pump working. When my lift pump went it would run fine then die. Wait a few minutes like 6spd05Dually and it would fire right up run fine for a while then just die again (more quickly if on the go peddle). I bumped the starter on the side of the road and very little fuel came out while pump running. Had the pump retrofitted to in tank and have not had an issue since.

Mark Hodowanec

You are spot on! It was just the lift pump. Sorry for the delay in posting the update on this. Gotta tell you guys, even though I was hoping that it was just a lift pump, I was very apprehensive until the truck was fixed. Thanks to all that replied & tried to help me!