Engine/Transmission (1998.5 - 2002) fuel pressure ?

[cmills]

My fuel pressure, taken off the top of the filter housing will run at around 15psi and then it will fall to around 10psi,(this is at an idle) it just kind of jumps back and forth its kind of like the lift pump is getting some sort of voltage drop, when I am driving it, it stays at acceptable levels. Is this normal or is something wrong?



thanks,



Cory

 

[BillGotthelf]

Cory I had the same thing happen to me. The screen at the bottom of the fuel tank had some crap in it plugging it up and causing erratic pressure readings. I lifted the bed and unscrewed the cap holding the fuel gauge sending unit, pickup and return. Cleaned out bottom of tank and screen in bottom of unit, replaced and no more problems.

 

[cmills]

fuel pressure

One thing I did forget to mention was that as soon as I rev it up the fuel pressure goes up to around 15 and but then if I hold it steady it will again drop, so if it was the screen in the bottom of the tank I wouldn't think that it would always jump up when I increase the RPM.





Cory

 

[rkressg]

These simptoms also represent a failing lift pump or possibly a clogged fuel filter. I would start with the path of least resistance, change the fuel filter; but it could be a dying lift pump.

-Rich

 

[cmills]

the fuel filter has less than a 1,000 miles on it so it shouldn't be that, I'll have to keep an eye on the lift pump, the pusher pump just went bad so have to get another one pretty soon, but I'll keep watching the pressure just in case. I just thought it just continually started to lose pressure or quit all the sudden, not go up and down.

 

[rkressg]

These pumps die in many different ways. Seeing one with erratic fuel pressures is a common occurance. Yes, they usually just become weaker, and then just fail. Others just outright fail one day with little warning. Having a faltering pump is an indication that the internals of the pump are wearing out.



You can also check the wiring to the pump. There might not be a good solid connection at the harness connection. Clean the contacts and re-pack with di-electric grease. See if this helps. You can also check the voltage at the lift pump using the bump and run method.

-Rich

 

[Ralph Heron]

LP fun...

Hi Cory,



My take is that your LP is out its way out... had the same condition. My symptoms were (all numbers are post filter readings):



1. startup: solid 13-14psi

2. idle: needle would jump from 7 - 13 psi

3. upon acceleration, would always get 13psi



Only noticed AFTER installing FP guage (of course... ).



After reading threads on LP pressures, all would report that as the throttle is applied, LP pressure would droop (I didnt see any of this but did have the jumping needle). Things got progressively worse over the course of two weeks at which point the min pressure got around 5 PSI and continued the jumping back to 13psi.



At this point, I dumped the $150 and replaced the LP. Now I get a constant 13 psi at startup and idle. Things ease down as low as 10psi at full throttle. Just hope that I didnt do any bad things to my VP44 in the progress but only time will tell...



Rgds,

Ralph-

 

[cmills]

Thanks Ralph, thats almost exactly what mine was doing it would actually be higher when accelerating, then today its starting to get lower even when driving and it isn't jumping up quite as high.



hopefully I can get it replaced under warranty since the pump is only 9 months old, I guess I will see, since next week it goes into Scheid Diesel to see why it cuts out and blows a bunch of blue smoke when I hit the throttle.