Engine/Transmission (1998.5 - 2002) Strange Fuel Pressures

[cD'amato]

I have a FP Gauge that gets the FP reading before the fuel filter. All of a sudden my FP is very erratic and significantly lower. I am assuming this means its time (58,000 miles) for a new lift pump? Is this correct?

 

[CoastyAV8R]

When my lift pump went, I would go from 12 psi to 0 psi to 3 psi then some times back to 0 or maybe back to 12 psi. Mine was all over the place. I verified the pump had stopped working when the gauge read 0 so I assumed the gauge was correct and it turns it was. I replaced the lift pump and my gauge showed 15 psi. I think different pumps die differently. Some go all at once, some beat around the bush. I would definitely check you gauge set up first, but don't be surprised if your pump is actually doing what your seeing.



Pat

 

[Mad Bomber]

Lift pump

When my LP went out it was all over the place as well. I double checked it by hooking up a 2nd fuel pressure guage and it was reading the same. I bought a new LP and problem was solved. Eric

 

[RustyJC]

Verify the gauge first. I've had Westach sending units go bad, and with some of the failures the needle swings all over the gauge. Since I have a dual gauge, I can check against the 2nd fuel pressure gauge, but I wouldn't change a lift pump until I verified the gauge readings.



Rusty

 

[Rockcrusher]

Originally posted by RustyJC

Verify the gauge first. I've had Westach sending units go bad, and with some of the failures the needle swings all over the gauge. Since I have a dual gauge, I can check against the 2nd fuel pressure gauge, but I wouldn't change a lift pump until I verified the gauge readings.



Rusty

Where and how is your FP gauge connected?

 

[RustyJC]

Originally posted by Rockcrusher

Where and how is your FP gauge connected?

The sending units are remote mounted on firewall. They connect through stainless steel-braided AN-4 lines to Ray's banjo bolt fittings at the fuel filter housing inlet and outlet. The post-filter sending unit uses a gauge snubber.



Rusty

 

[RobbyRam]

Try BriarHoppers fuel pressure test gauge.

Bob in Sacto

 

[azpete]

My low pressure readings went on for about 5 days. Now all of a sudden they are back to the original pressures and have stayed there for almost a week. Wanted to take off for the Labor day weekend and don't have enough time to move the lift pump so I am going to buy a stock one and decide wheather to put it in or just take it with me. Hate to see the old one go because it always put out such good pressures- 16 at idle- 13-14 at any cruise speed and no lower than 9-10 even with the comp at 5x5.

 

[rweis]

A thought,



Run a tank of fuel lubricant through it. Maybe the pop off spring is sticking or the vanes are not going all the way out by the centrifugal force of rotation. Or of course the pump rotations are going screwey.



I run a fuel lube in every tank because some of the fuel refineries are starting to go low sulfer getting ready for 2006 standards, specifically BP I think.



Bob Weis

 

[cD'amato]

Even when the gauge was brand new with a fresh fuel filter my WOT pressures were 6PSI and my idle readings were 11 or 12 PSI. This is acceptable right or should I have the lift pump changed? It is covered under the 100k mile warranty right? The truck just hit 56k miles everythings original except the rotors, brakes and brake lines.