Low fuel Presure

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Sep 3, 2004 | 06:57 PM

champdog

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Joined: Apr 2004

Posts: 23

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Low fuel Presure

Hi every one. I have a small fuel pressure problem. its on a 98 F-250LT 5.4. I am running 30lb of pressure with vacuum and 40 with out. I am told that the pressure should be at 40 to 50lb. The big question is? How do I get the pressure up even though I have put a new pump and filter in? I have also tried a new regulator and it had no change. I put the old one on and got my fifty bucks back. I already spent 200 in a new pump I did not need to. Is there something I am missing or is there an adjustable regulator out there. I am Getting a P-171 P-174 code and this is the last problem that I can think of too fix it Thanks

Last edited by champdog; Sep 3, 2004 at 07:00 PM.

Sep 3, 2004 | 08:41 PM

Racerguy

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Joined: Aug 2002

Posts: 12,679

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From: BC, Canada

Hi champdog and welcome to the forum

According to the shop manual the fuel pressure should be 30-45 psi so your's is ok.

Have you closely checked for vacuum leaks? Especially the PCV hose.
Have you cleaned your MAF sensor?
Is the rubber grommet that the MAF wiring goes through in the air box ok?
IAC inlet hoses hooked up to the air intake ok?

If you're still not able to figure it out it might be time to cut your losses and take it in to your dealer and have them check it. They can monitor live data from the PCM and see how the MAF, O2's etc are working.