slow drop in fuel pressure

CaptainChad · June 27, 2020

Aloha,

been having this problem with my 01 2500 6.0L for MONTHS! Im pulling my hair out!

The truck runs great when its on, however when I turn it off, the fuel pressure slowly falls. all the way to 0. New Fuel pump installed, new fuel line, new fuel filter, new injectors, plugs, wires, new fuel pump regulator, new ignition, and I even installed a second check valve in the fuel line above the fuel pump to eliminate the possibility of the fuel pump check valve being the issue. The truck take 2-3 times to start. Ive even pulled up the fuel injectors and checked for leaks, I did find a few leaky injectors and switched those out. I still cannot find where the fuel pressure is going. no fuel coming out of the FMR vacuum hose. The FPR is not OEM, could this still be the problem? I pinched the fuel return line and checked fuel pressure and it still leaks down slowly. My gut is telling me its the off market FPR? im not seeing any fuel coming from the injectors when I lift them from the holes. PLEASE help!!!!!!

CaptainChad · June 28, 2020

to add to this, the fuel pressure while running is 52psi. pressure jumps 5-7psi when I remove the vacuum hose from the FPR. it takes approximately 20 min before the fuel pressure drops to 20psi. it takes at least 10 minutes before there's any drop in pressure after truck is turned off. PLEASE HELP! Ive been at this for almost a year...

grandpalarry777 · June 28, 2020

This may be totally out in left field but, did you check the fuel filter housing for hairline cracks? Perhaps a fine crack is letting enough air leak into the system when it sets for a while and you lose prime.