Engine/Transmission (1998.5 - 2002) fuel pressure vp44?

[dieselsam59]

I am losing fuel pressure when under light or no load. My gauge drops from 12-13 to 6-7psi. As soon as i step on the throttle my fuel pressure comes up with my boost. Could the injection pump be returning to much fuel to the tank. lp was replaced about 9,000 miles ago and seems to work fine now, sounds good and builds pressure with a starter bump

 

[dieselsam59]

I checked for codes-- everything is clear

 

[SEmerson]

I think you lp is bad.

 

[jjohn]

I could be your check valve opening, as you give it more throttle, use more fuel and drop pressure the check valve closes and brings up the pressure? Just a guess... I have a little of that going on also with my pusher pump + stock LP.

 

[dieselsam59]

i now have two codes: p1693 and p0500 is this related?

 

[cumminspwr01]

P0500 is no vehicle speed sensor signal P1693 is a companion code

 

[mmclaughlin]

The fuel pressure issue you are having was exactly what I saw just before my second lift pump died. It first started to drop just a psi or 2, then it was like 5 or 6, then the big drop - 2psi, so out with the lift pump and in with the FASS. I've got a little over 10k on the pump and it's rock-solid at 15 psi. I would at the very least change out the LP if you don't want to dish out the $$ for the FASS or something comparable. You could always do a relocation of a new carter pump and from what I heard, works very well and much more inexpensive. I figured $600 was worth every penny for piece of mind and great fuel pressure (not to mention wick easy draining of the water seperator and chaning of the fuel filters).

 

[Oil Burner]

I know of one lift pump that was bad right out of the box, so don't be shocked that it is bad at 9,000. Stuff happens, but I would say the pump is going south.



My second LP is still alive, but I am saving for a FASS right now.



-Jason

 

[dieselsam59]

Two days ago when filling up with fuel I heard the engine stumble, i looked at the fuel psi gauge and it had dropped. All was fine until i left . When i pulled out it shook and missed with no power. When i finally got to 60mph my tach read 2200 but should have been 2000 and then it read 1800rpm and 63mph.

It was after this that i discovered the new codes. Makes sense with the p0500 -- vehicle speed sensor, but, i am sure this is related to my fuel psi. I installed my mechanical fuel gauge and pressure does same thing.



Should the engine change speed and sound at mid rpms in neutral If i hold the the throttle at say 2000 rpms it holds for about 4 seconds and then raises to 2100. if i hold at 1800 rpm it drops to 1700rpm and engine sounds much smoother with the change in speed.



Acts the same with fuel psi or not .

 

[Rattlin_Ram]

Not to get too far off subject, but what exactly is meant by "Companion Code"? I've seen it said several times on here, but don't understand what it means.

 

[cumminspwr01]

P1693

DTC Detected In ECM Or PCM It is more or less a code telling the system that the DTC detected a code. The important code to us is the one that comes after the companion code.