Have a friend with a 2nd-Gen 24 vavle (I don't know the exact year...) that he just replaced the lift pump on. He used a unit he sourced through NAPA, supposedly a new (not reman) Carter? Anyhow, at the same time he installed a fuel pressure gauge using the banjo bolt setup. He bled the air out of the system, finished up the installs, and climbed in the truck to test it out. He turned the key and watched the fuel gauge as the pump cycled: dead on at 15psi. Next he fired the truck up, and fuel pressure instantly dropped to 5psi????? Upon light throttle input, reading went to 0psi and stayed??? He immediatly shut the truck down, let it sit for a second while he looked for leaks, but found none. So, he tried it again, with identicle results!! What would cause the gauge to read good pressure with just the key on, but low with the truck actually running and then drop to zero with load? Did he just get a bad lift pump?? Possible install problem? Thanks for any thoughts!!

 

Its one of two things either a defective lift pump or gauge.

 

I vote for a miswired pump, would be easy since it was replaced with a non EOM version with a different wiring harness.


phox

 

I know nothing about the system, so please help me out here. Is the stock lift pump wired with a plug type connection, or would it be a snip-snip type deal to remove it? How many wires? What are the wire functions?

 

Those pumps from Napa are direct replacements and come with the same harness Cummins sells. Thats what I have on mine.The only thing different is Napa warranties for a year and Cummins for six months.

 

Gotcha


phox

 

Hmmm, well, any other ideas out there??

 

The cummins computer on the side of the block is what controls the lp if it draws to many amps it will cut it back or either cut it off what u can do is wire in a resistor so the computer is reading what it needs to read get somebody with a wiring diagram and that know how to read it and y'all ought to be able to fix it up

that may have been the problem in the first place i ahd the same thing happen onl my last truck

Jake

 

another idea try replacing the fuel filter it may be stopped up