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how to diagnose a fuel pressure regulator

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Old 04-06-2009, 07:07 PM
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Anyone?
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Old 04-06-2009, 07:19 PM
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Originally Posted by shutzero View Post
Well is 50 psi a bad fpr? I'm assuming it is, would this also be the reason my car is idling higher than I have it tuned to?
Do you have factory FPR?
50psi is high, should be around 43.5psi
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Old 04-06-2009, 07:20 PM
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Yes I do have the factory fpr
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Old 04-06-2009, 07:32 PM
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shbox site says what fuel pressure should be, might be worth taking a look. I cant really say if the FPR is bad. Since you don't have fuel on the vacuum side.

http://shbox.com/1/4th_gen_tech2.htm...essure_testing
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Old 04-06-2009, 08:06 PM
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Yea I don't think there's any fuel coming out of it?
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Old 04-06-2009, 10:07 PM
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Could this still be the fpr?
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Old 04-07-2009, 01:22 AM
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What does the psi do when your problem occurs on start up? Does it hold psi? 50 is a bit high but shouldn't cause your symptoms.
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Old 04-07-2009, 06:02 AM
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well as it is it idles higher than its set to, but i didnt get it to startup weird with the gauge on
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Old 04-07-2009, 07:51 AM
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50psi with the vacuum line attached?
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Old 04-07-2009, 08:15 AM
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Yeah with the vacuum line connected it reads 50 psi when it primes and when it idles
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Old 04-07-2009, 02:39 PM
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Anyone else?
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Old 04-07-2009, 04:38 PM
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Pressure is way too high for idle and even for WOT. Max pressure w/out vacuum or at WOT should be 43.5psi or between 43 and 45psi.

Last edited by SS RRR; 04-07-2009 at 04:44 PM.
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Old 04-07-2009, 05:02 PM
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Hi, I have same problem, there is not fuel coming out from FPR , the fuel pressure is 50 psi at idle and 60 psi without vacuum line....no fuel inyectors leaking, so I am 99% sure, my fpr is bad. The idle is a little high and some times I have to turn the key 2-3 times to get it start. My fuel pressure drops almost immediately to 0 psi when engine is not runnig.
What other symptoms do you have?
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Old 04-07-2009, 06:22 PM
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I've just got the high idle and problems starting if I don't prime the car
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Old 04-07-2009, 09:25 PM
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Originally Posted by Ger-Fire View Post
Hi, I have same problem, there is not fuel coming out from FPR , the fuel pressure is 50 psi at idle and 60 psi without vacuum line....no fuel inyectors leaking, so I am 99% sure, my fpr is bad. The idle is a little high and some times I have to turn the key 2-3 times to get it start. My fuel pressure drops almost immediately to 0 psi when engine is not runnig.
What other symptoms do you have?
the pressure dropping to 0 sounds more like a pump related issue
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Old 04-08-2009, 12:16 AM
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If the pressure drops off that quick, would be cause any one of these reasons leaking injector, leaking lines or fittings, leaking FPR, or bad check valve on the pump.
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Old 04-24-2009, 06:03 PM
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got the new fpr on...i cant tell yet if it fixed the problem but it actually does seem to be idling lower...ill have to throw a tech II on there to read rpms to see if it helped
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Old 04-24-2009, 07:16 PM
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So the fpr didn't fix the startup problems...any other ideas as to what it could be?
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Old 04-24-2009, 09:12 PM
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Anyone?
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Old 04-24-2009, 09:29 PM
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With a fuel pressure gauge hooked up and system primed with engine off does the fuel pressure drop to 0 immediately? If so, I would be willing to bet it is the check valve in the pump.
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