Engine/Transmission (1998.5 - 2002) FP Question

[Big P]

I've had alot of problems with my fuel pumps within the past year and now they are starting again. I have two Carter pumps, lift and a pusher, and if they are bad they will be replaced with a PE4200. I have an Autometer electric fp gauge, but I don't believe it to be the most reliable gauge. Anyways, after extended driving 30+miles fuel pressure begins to fall, eventually to 0psi. The truck still seems to run fine while the gauge is at 0psi. While the truck is idling at 0psi, I cracked the hose to the fp sender and there is a steady stream of fuel that will flow out. My question is if there really is zero pressure, and the injection pump is pulling the fuel itself, shouldn't the hose to the fp sender be under vacuum? I am going to get a mechanical test guage next week to double check the pressure. BTW while at 0psi I can hear both pumps running. Any ideas?

 

[illflem]

I'd say you are following the right course of action to check the FP gauge first, quite often the sender is the only problem with the fuel system, they just don't last. Seems if the pressure was really zero that when you opened the line it would have sucked air causing the engine to stumble.