Engine/Transmission (1998.5 - 2002) Weird Fuel Pressure Readings..... While driving..

[MatthewW]

Ok my I was crusing down the Interstate this moring and the fuel pressure gauge while going 70mph... would go from the normal 10psi down to 5psi and then back up and then back down. . you get the picture. . Has never done this before. .



Is this a sign of the pump starting to give out or is this a new one to all? Ideas?





Matt W

 

[DwayneKelch]

Matt,



My experience with two LP failures were different. My idle pressure slowly decreased, but my cruising and WOT dramatically took a dive. Too, my LP pressures didn't vary back and forth like yours.



Do you have an electrical sending unit, or is gauge mechanical? Knowing this might help diagnose the problem.



Dwayne

 

[RustyJC]

I've had electrical sending unit failures that sounded like that. Steady normal readings, then the needle will swing wildly, stop somewhere (like 5 PSIG) for awhile, swing some more, stop at 10 PSIG, swing around some more..... well, you get the picture.



Rusty

 

[MatthewW]

it a a manual gauge. . DiPricol gauge with the isolator under the hood. It is hooked up to the schrader valve on the fuel filter housing.

 

[jdkenyon]

The last time my lift pump went south it started acting the same way. My wife and I were just starting a 600 mile trip and my guage went from running 12psi down the road and then drops a couple psi and jumped back up to normal. This kept getting worse until the pressure was dropping to 0psi and then jumping back to normal. Finally about 90 miles into the trip the gauge dropped to 0 and stayed there until we got off the road. It would show 3-4psi idling but as soon as you wind it up a little 0psi is all it would do. Took it to the dealer the next morning and they said it was definetly bad and replaced it under the 5yr/100,00 engine warranty.