Engine/Transmission (1998.5 - 2002) Fuel pressure guage

[Red Rocket]

I have a westach guage, and put it in with a rubber hose from the injection pump test port, including a needle valve open just enough to show the readings. Problem is for the first two weeks or so, I saw 6psi idle to 2 or less WOT. Then, it suddenly changed to 15psi idle and 10 WOT. The needle doesn't fluctuate, and gives nice smooth readings, except for the times I have seen it go straight from 13 cruising to 3, instantly.....

Any Ideas?



Thanks, Nick

 

[emjay]

Is that an electrical gauge or mechanical? If it's electrical, it could be a short in the sensor, wire, or gauge itself. Poor grounding may also be a culprit.

 

[RBSOB]

RR, what did you find. EmJay is right, a good ground for the sending unit is critical. Yours may be loose or intermittant. Test it or try relocating. Jim G.

 

[Smills]

I have a needle valve also I run it completely open just and idea.

My gauge is steady to.

 

[Red Rocket]

This is an electric guage, and it is grounded straight to the battery, not the original location, but made no improvements when I moved it from the body to battery.

 

[emjay]

One more thing, if the sender has only one wire, the sender case needs to be grounded, too. The only other way I can think of to verify it is remove the sensor and apply regulated air pressure to it, monitored with a second gauge. How many wires are on the sensor?

 

[Motorhead]

Hey, What a coincidence!! I installed a westach gauge into my brothers '01. 5 HO today and it does the same thing. It started at 15 psi at idle and as we went down the road it suddenly dropped to 6psi and 2 at WOT. You can shut it off hot and re-start it and it will read high again then drop. I checked the fuel pressure at pre filter with a mechanical gauge with the Westach hooked up also at the inj pump. The mechanical gauge read similar pressures and fluctuated the same as the electric gauge does. Do you guys think that the pressure relief might be sticking or is the lift pump acting up. Is the relief valve serviceable? The truck has 20,000 mi.

I was just opening up this page to post the same problem!!!

I'm going to ck it out in the AM.

PLEASE give me any ideas as my brother has to drive 225 miles home tomorrow THANKS, Chris

 

[emjay]

I am by no means an expert on the subject, but I read over the manual, and it states that the fuel pressure should be no less than 10 psi at idle, 6-7 psi cranking. The only other test is a restriction (vacuum) test on the tank side of the lift pump, which is a big hassle.



I think I have read that pressure can drop as low as 2 psi under WOT, perhaps someone else can confirm or deny this.



All of this speculating begs the question (please excuse me if it has been asked and answered a hundred times over):



Wouldn't a higher flow lift pump be able to deliver higher pressures at WOT? Has anyone tried using one of those high-flow fuel (gasoline) pumps in place of the lift pump? Since the injection pump needs fuel to cool and lubricate it, wouldn't a higher flow lift pump be better for the injection pump?



Also, having a keen eye for the obvious, higher flow injectors and other mods that increase fuel flow would only make the problem worse, right?

 

[dmurdock]

Originally posted by emjay



Wouldn't a higher flow lift pump be able to deliver higher pressures at WOT? Has anyone tried using one of those high-flow fuel (gasoline) pumps in place of the lift pump? Since the injection pump needs fuel to cool and lubricate it, wouldn't a higher flow lift pump be better for the injection pump?

Yes, this gets covered occasionally... do a search on lift pump or pusher pump and you'll have an encyclopedia of information...

 

[Chipstien]

BE CAREFUL!!!!!!!!!! When my lift pump went out it would change psi quickly. I thought it was the guage too.