Engine/Transmission (1998.5 - 2002) Fuel preasure question

[SCREAMNEAGLE]

I have a friend that installed a Powermax3 and 275 intectors on his '01 HO. At an idle he has 15psi. Running down the road 6 to 10 psi depending on his driving. But, sometimes just running down the interstate, it will drop to zero and then come back up. It's a Westach gauge. Is this a problem with his gauge or a pump problem? It doesn't run bad, and I know he's tried bleeding it thinking he may have an air pocket.

 

[pwr2tow]

Put a mechanical gauge on to test if his gauge is working properly but I would guess his lift pump is on it's way out, that is exactly the way mine act before they go out completely, I have replaced 4 lift pumps includeing the original factory one.



One more thing you might want to check is the relay in the power distribution box. I had a bad relay once that I thought was the lift pump going out, they act the same on, off, on, off, pressure up, pressure down, pressure up, pressure down, like turning the key on and off.



Ron

 

[TomGolden]

My own gut feeling tells me his lift pump is DOA or dying quickly.



I had 45K miles on my original lift pump with no fuel pressure

gauge. Truck ran like a dream. I put my FP gauge on, read <<10

PSI... dead lift pump. I have no idea how long it had been

dead at that point. I swapped it out, fortunately my VP44 doesn't

seem to have suffered any significant injury.



So it is entirely possible for the LP to be dead or on it's last legs,

and still have the truck seem to be running strong as ever.



Tom

 

[GeneralMachine]

Fuel Pressure

If it where me, I would hook up a manuel feul guage to double check the press. You can go to any auto store buy a R-12 freon charge hose hook it up to a manuel guage tape it tp the windshield and go for a ride, then you will know. If his press is dropping he sure needs to get that fixed Good luck Harv

 

[rblomquist]

Hook up a manual gauge and compare. Most likely the pump is going south, not dead. A dead pump will show zero psi to creating a vacuum. My neighbor's 99 ran great and started just fine but I talked him into putting my Briarhopper gauge on and it was sucking a vacuum-that's a dead pump!