Engine/Transmission (1998.5 - 2002) Fuel pressure problem!

[Milo Pig]

Just installed an Auotometer electric fuel pressure gauge and everything was reading normal, 15psi at idle and 12 - 13psi at a 65mph cruise and 10psi at WOT. On a 40 mile trip the gauge decided to wave at me a little bit and now at cruise it reads a steady 8 psi and as soon as boost is needed (hills and such) it drops to 5psi at 20+psi of boost.



I have totally rebuilt my fuel system: -8an bulkhead at the bottom of the tank, -8an line to suction side of Carter 4601 fuel pump mounted on the frame, then -6an line all the way through the filter housing, then -6an line int the injection pump. Fuel pressure sending unit is in line between the filter housing and injection pump. This system is a month old.



Mods to date is MBRP 4", Edge EZ, BHAF, and the fuel system mentioned above.



Ideas or tests I can do? Oh, there is no codes in the PCM.



Thanks,

Sean

 

[GOT-Torque]

How's the fuel filter?

 

[JFaughn]

I haven't worked on that yr. & mod. yet but all fuel injection [ gas or diesel ] uses the pump to make volume but pressure is controled by return [ fuel pressure regulator ] so look for that it may be getting weak -lower pressure.

 

[Milo Pig]

Fuel filter was changed when the new fuel system was installed, so a month old. Roughly 800 miles ago.



Is there a fuel pressure regulator some where that I do not know about? I didnt think there was one.



Thanks,

Sean

 

[GOT-Torque]

The first mod I did to my truck was the big fuel line kit and relocated the lift pump. Next I installed guages and for the first day and a half, pressure seemed ok. I don't remember exactly what it read but it was around 14 at idle, 13 cruising, 12 WOT. The 2nd day with gauges on my way home from work the gauge started to periodically show less than 5 lbs. Over the next two days, it became worse until it would not hold 4 psi cruising.



I don't know if I was just lucky enough to happen to install my gauges 2 days before the failure of my lift pump OR if by changing to big fuel lines and fittings it somehow pushed my worn pump over its limit causing it to fail.



Bottom line is I put in a new lift pump and all is well. 15. 2 psi idle, above 14 cruising, and just under 12 at WOT.



Might try a known good lift pump to see if still occurs.



I may be wrong on this one, but I believe the pressure regulator or pressure relief is internal to the VP44 and anytime pressure is above 14psi, it routes fuel back to the tank

 

[Milo Pig]

The first mod I did to my truck was the big fuel line kit and relocated the lift pump. Next I installed guages and for the first day and a half, pressure seemed ok. I don't remember exactly what it read but it was around 14 at idle, 13 cruising, 12 WOT. The 2nd day with gauges on my way home from work the gauge started to periodically show less than 5 lbs. Over the next two days, it became worse until it would not hold 4 psi cruising.



I don't know if I was just lucky enough to happen to install my gauges 2 days before the failure of my lift pump OR if by changing to big fuel lines and fittings it somehow pushed my worn pump over its limit causing it to fail.



Bottom line is I put in a new lift pump and all is well. 15. 2 psi idle, above 14 cruising, and just under 12 at WOT.



Might try a known good lift pump to see if still occurs.



I may be wrong on this one, but I believe the pressure regulator or pressure relief is internal to the VP44 and anytime pressure is above 14psi, it routes fuel back to the tank

This is a carbon copy what is happening to my truck. I will be giving summit racing a call to see if they will warrenty this brand new Carter 4601 pump. I will put my old lift pump on and see what happens.



Thanks for the replies.

Sean

 

[stg2500]

I am having a similar problem with my truck. I installed the Westach 16 psi guage on my stock truck. The guage reads anywhere from 0 to 12 psi within a minute. The guage read accurately for about a week. Normally running at 40 - 50 mph the guage reads 2-4 psi. I verified that the lift pump was good when I changed the fuel filter last weekend. Any ideas?

 

[RAJohnson]

Just installed an Auotometer electric fuel pressure gauge and everything was reading normal, 15psi at idle and 12 - 13psi at a 65mph cruise and 10psi at WOT. On a 40 mile trip the gauge decided to wave at me a little bit and now at cruise it reads a steady 8 psi and as soon as boost is needed (hills and such) it drops to 5psi at 20+psi of boost.



I have totally rebuilt my fuel system: -8an bulkhead at the bottom of the tank, -8an line to suction side of Carter 4601 fuel pump mounted on the frame, then -6an line all the way through the filter housing, then -6an line int the injection pump. Fuel pressure sending unit is in line between the filter housing and injection pump. This system is a month old.



Mods to date is MBRP 4", Edge EZ, BHAF, and the fuel system mentioned above.



Ideas or tests I can do? Oh, there is no codes in the PCM.



Thanks,

Sean

Not sure but you might want to read thru this thread, there is a lot of talk about the 4601 pump. https://www.turbodieselregister.com/forums/showthread.php?t=141924

 

[Milo Pig]

Just ordered a Mallory 140 and regulator. Not gonna fool with the Carters anymore. There are to many bad stories on the Carters.



I will update when the new pump is installed.



Sean