unreal_news

Im having some fuel issues on my car.

I measured the following using clarks instructions
--> http://www.clarks-garage.com/shop-manual/fuel-01.htm

pressure when car is off and pump started (38psi)
pressure when car is idle (33-38psi) // thats double what it should be
pressure takes forever (like 1.5+ hours) to relieve back to 14psi

anyways, I thought i should start by checking the FPR and Ild like to know if im on the right track. Heres what i did...

I took the porsche air tire compressor and hooked one end up to the input of the 'Stock' FPR, cut it on and the input pressure gauge quickly climbed to 80psi before i cut it off. I didnt notice any air comming out the outlet hole. Is this any indication of a busted FPR? or would no pressure build up on a busted one?

any assistance appreciated, and thanks,
-john

unreal_news

btw, the tube on the vaccume tube side is not connected.

perhaps a better question is, how does a FPR work?

83na944

I assume you've got an 8 valve car.

If I read Clark's correctly, you FP at idle is correct at 33 psi. And the leakdown is good since it takes longer than 20 minutes to reach 14 psi.

I've never torn a FPR apart, so I don't know how the inner parts. The FPR works by returning fuel to the gas tank when the pressure rises above the set level. I've always assumed that there is a diaphram that deflects and uncovers a port or opens a valve when the pressure is too high.

The vacuum line attaches to the intake. As the throttle opens, the manifold vacuum rises. I assume that this vacuum somehow increases the pressure set point of the FPR so that more fuel can be delivered to the injectors.

Sorry I can't give tou details.

What problem are you having?

unreal_news

heh, well, problem was last time i drove it i saw white smoke from the engine and a few flames out the tailpipe (friend notified me of flames as he was driving behind me).

anyways, i dont have the $$ right now to take it to a mechanic as i just used 2grand for some simple maintenance. so I really have to do this myself. that aside...

the fuel pressure is way too high during idle (though im going to do a 2nd test to verify), i thought mabey the FPR was busted, but I wasnt sure how to test it. I hate to troubleshoot by replacing parts until the car runs properly.

anyway, I've started the car twice since I cut it off about a month ago and during the short period of time i allow it to run, it seems fine.

-john

unreal_news

I guess ill mention that the belts look fine (brand new in fact, so i guess smoke wasnt from the belts).

unreal_news

oh, i just noticed i was wronge about the idle psi. Im going to do another test and see what values i get.

Zero10

Mine is 40psi jumpered, 32psi idle.
It will NOT drop down to 14psi. It stayed at 32psi for 9 days, before I decided it was staying there.
Just for comparison.

I talked with Clark over at Clark's Garage, and he felt this was nothing to worry about.

unreal_news

zero10 -> i really appreciate that, thank you tons . anything I can eliminate will help.

well, perhaps some of my fuel is old and is causing the valves to stick, perhaps i should just run it for a bit (with a close eye) and put some fuel cleaner in.

ill be sure to post back later

Zero10

What exactly is the problem?

Causing the valves to stick, do you mean the fuel injectors themselves?

unreal_news

well, i had flames out my tail pipe last time i really drove it (over a month ago). Ive started it about 3 times since for short periods of time with no issues. belts looks good, fuel pressure is probably good (doing another test tomorrow). so I was thinking an out-take header valve was sticking, allowing fuel to escape? not sure, i may need to run the car for a couple of minutes so I can see where the smoke is comming from and check for flames?

Zero10

Ah I see. I must not have seen any other threads on this matter.
Flames out the exhaust sounds like it's running really rich. If you do a compression test, you can verify if you have a stuck valve.
I'm not terribly good at troubleshooting a running rich problem, but I'd lean towards the O2 sensor?