Hello again everyone. This is Myles the piano rebuilder with MORE problems on my 2002 24 valve 4x4 truck, 96,000 miles. After having my lift pump and injector pump replaced under warranty about 3,000 miles ago, I noticed today that I was starting to lose power going up a long hill. I glanced down at my fuel pressure gauge and saw some low readings.....idling at 10psi and cruising at 5-7psi. This immediately alarmed me and I turned around and babied it back home. On my way, I noticed that occasionally the pressure would go back to where it used to be...15 at idle....10-12 under throttle. Then it would dip back to the lower readings again.

When my mechanic replaced the two pumps a little while ago, he also did a fuel filter change as well. In fact, I called him today and he said maybe my fuel filter was plugged up and that was why the readings were jumping around. Is it possible that that could be the problem?

I did an ignition recycling 3 times to see what codes would come up, but instead of getting numbers, all that came up was "P PCU" and "P ECU". Do these mean anything?

I figured I'd run this by you "seasoned" Dodge fans to get your opinions. After all, what does a pianoman know about diesels anyway!!!

Thanks guys.....
Myles

 

P PCU and P ECU are the two places codes are read from. If you got a series of dashes and a donE, then you do not have any stored codes. If any numbers came up (P ####), those would be the codes. Sounds like everything is fine, from a Codes standpoint. I am pretty new at the Cummins diesel diagnostics, so I'm sure someone else might chime in here. Maybe the new lift pump is going south?

 

If your readings are taken after the filter, it's probably time to change it. (Might still be a failing pump though)

It they're taken before the filter, I say your lift pump is the culpret.

Check to be sure all your wiring connections to the pump are clean & tight.

zulusafari,
That line in your sig cracks me up.

 

You might also want to check your fuel lines back to the tank for air leaks. Might make the pressure drop...

Just my 2 cents...

 

mrpiano458nte, I would also recommend watching the fuel level to see if the problem goes away with a full tank. When mine drops below 5/8, I start getting air in the fuel line -- too much for the FASS to remove. I believe the pick-up tube (duck bill valve) is causing the problem, and will be fixing it later this week. You stated that your FP went back to normal while going down hill -- the fuel would have been in the forward part of the tank due to gravity (the pick-up tube is closer to the front). Try filling up and heading back up the hill to see what happens.

Franklin

 

I thank all of you for trying to help out. I took the truck to my local mechanic today and he changed the fuel filter but that did not help. He did a bunch of tests and found that the lift pump is starting to go again. So it appears that Chrysler will be responsible one more time for replacing it free of charge! Why can't they produce a pump that doesn't constantly break down? This is my third one! Good thing I caught the problem before it took out the Injector pump.... I'll keep in touch and report back once the problem is solved. Thanks again guys!

 

And Cummins doen't recommend Fuel aditives.

I have used Diesel Fuel additives for lubricity in every tank full.
2nd lift pump still shows 16 psi @ idle, 10 @ WOT 40,000 miles later.

 

Wonder why?

Maybe because they know it will help fix the problem with the LP's and IP's

Like everything today they design it to fail at point or another!