Fuel pressure regulator help
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Joined: Feb 2007
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From: Woodville Alabama
Fuel pressure regulator help
I'm trying to diagnose hard starting issue on my 90 coupe. Hard starts both when cold or hot. Fuel pressure guage reads 46lbs with key on. holds 36lbs with engine running but drops to 0 within 10 seconds when shut off. FSM diagnostics says injectors or fuel pressure regulator and to pinch off return line to test regulator. Vacuum line has no smell of fuel. This is a 90 and has NO soft section of hose to pinch off, unless its back behind the tank somewhere where I cant access.
Anbyone know how I can determine fpr or injectors. Injectors have been ohm test and check ok. Yhanks
Anbyone know how I can determine fpr or injectors. Injectors have been ohm test and check ok. Yhanks
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
is a 90 and has NO soft section of hose to pinch off, unless its back behind the tank somewhere where I cant access.
Wrap a rag around the tubing and use vice grips to clamp it. Turn on the ign switch. If pressure holds when the return line is clamped the FPR is ok.
Have somone turn on the ing switch and immediatly clamp the pressure line to check the FP check valve. If pressure holds the check valve is ok.
If both test pass, the leak is either in the injectors on fuel lines.
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From: Cumming Ga
Remove the fuel filler cap and pull out the rubber surround to reveal the flex fuel lines; of the two to the right side, one is pressure, one is return.
Wrap a rag around the tubing and use vice grips to clamp it. Turn on the ign switch. If pressure holds when the return line is clamped the FPR is ok.
Have somone turn on the ing switch and immediatly clamp the pressure line to check the FP check valve. If pressure holds the check valve is ok.
If both test pass, the leak is either in the injectors on fuel lines.
Wrap a rag around the tubing and use vice grips to clamp it. Turn on the ign switch. If pressure holds when the return line is clamped the FPR is ok.
Have somone turn on the ing switch and immediatly clamp the pressure line to check the FP check valve. If pressure holds the check valve is ok.
If both test pass, the leak is either in the injectors on fuel lines.
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Joined: Feb 2007
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From: Woodville Alabama
Thanks LT1spirit and 65z01, I was able to get to the soft hoses to clamp it. After starting engine pressure did hold but at about 62 lbs which is high. According to chart 7 page 2 of 2 (6e3-A-29), the high pressure indicates bad fpr. Any body agree or disagree? ( No restrictions in the line BTW)
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From: SE NY
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Sorry but pp 6e3-A-29 in my '88 FSM is about Code 15...
Anyway I don't think high pressure is an indication of FP failure with the return line clamped. Since the FPR cannot releive the pressure back to the tank it should go to the max of the FP, IMO??
Since pressure held with the return line clamped, sounds like you have a FPR issue, with injectors, FP check valve and lines being ok.
Anyway I don't think high pressure is an indication of FP failure with the return line clamped. Since the FPR cannot releive the pressure back to the tank it should go to the max of the FP, IMO??
Since pressure held with the return line clamped, sounds like you have a FPR issue, with injectors, FP check valve and lines being ok.
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Thread Starter
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Joined: Feb 2007
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From: Woodville Alabama
Sorry but pp 6e3-A-29 in my '88 FSM is about Code 15...
Anyway I don't think high pressure is an indication of FP failure with the return line clamped. Since the FPR cannot releive the pressure back to the tank it should go to the max of the FP, IMO??
Since pressure held with the return line clamped, sounds like you have a FPR issue, with injectors, FP check valve and lines being ok.
Anyway I don't think high pressure is an indication of FP failure with the return line clamped. Since the FPR cannot releive the pressure back to the tank it should go to the max of the FP, IMO??
Since pressure held with the return line clamped, sounds like you have a FPR issue, with injectors, FP check valve and lines being ok.
i may have got lost in this darn diagnostic tree. I'll start over and post again. I think I need to get a degree in reading the FSM!
Melting Slicks
Joined: Jan 2008
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From: Jasper Texas
Here you go, this might help you out:
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Some slight differences, but basically the same.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Some slight differences, but basically the same.
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Joined: Feb 2007
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From: Woodville Alabama
OK ...I've run the diagnostics again and this is what it leads to. 46lbs with key on, pressure drops to 0 as soon as pump stops running. Pinched off return line and pressure holds at about 62lbs. According to FSM this leads to faulty pump. Any comments? thanks. BTW this is on a 1990 L-98...vin8 Diagnostic chart is acually 6E3-A-23, not what I stated in earlier post. That was chart for vin J. Thanks
Thread Starter
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Joined: Feb 2007
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From: Woodville Alabama
Here you go, this might help you out:
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Some slight differences, but basically the same.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Some slight differences, but basically the same.
Safety Car
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From: :45 minutes from everywhere / E-I-E-I-O
OK ...I've run the diagnostics again and this is what it leads to. 46lbs with key on, pressure drops to 0 as soon as pump stops running. Pinched off return line and pressure holds at about 62lbs. According to FSM this leads to faulty pump. Any comments? thanks. BTW this is on a 1990 L-98...vin8 Diagnostic chart is acually 6E3-A-23, not what I stated in earlier post. That was chart for vin J. Thanks
I don't think bad injectors wouldn't let the pressure off that fast, even if the car was running!
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Joined: Mar 2008
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From: Cumming Ga
OK ...I've run the diagnostics again and this is what it leads to. 46lbs with key on, pressure drops to 0 as soon as pump stops running. Pinched off return line and pressure holds at about 62lbs. According to FSM this leads to faulty pump. Any comments? thanks. BTW this is on a 1990 L-98...vin8 Diagnostic chart is acually 6E3-A-23, not what I stated in earlier post. That was chart for vin J. Thanks
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From: Woodville Alabama
Jon...thanks for pointing that out.I ran the diagnostic wrong again. Here is the latest run. ignition on...pinched off PRESSURE line...did not hold...ignition off. Ignition on...pinched off return line...pressure did not hold. So this indicates (according to FSM) leaking fuel injectors. Guess this is your department! I really didnt think that an injector issue would allow the fuel pressure to bleed off that rapidly. The pressure drops from about 45 lbs to 0 almost immediately. The car does not run THAT bad after it starts
Safety Car
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From: :45 minutes from everywhere / E-I-E-I-O
If the fuel was 'dumping' out of the injectors like that, it WOULDN'T be spraying into a mist, and it wouldn't run. AND, I think you'd be getting a hydraulic cylinder lock from gasoline dumping into a cylinder when it was not running. Then the crankshaft would stop turning when you're starting the motor.
Isn't that right Jon?
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Joined: Mar 2008
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From: Cumming Ga
Jon...thanks for pointing that out.I ran the diagnostic wrong again. Here is the latest run. ignition on...pinched off PRESSURE line...did not hold...ignition off. Ignition on...pinched off return line...pressure did not hold. So this indicates (according to FSM) leaking fuel injectors. Guess this is your department! I really didnt think that an injector issue would allow the fuel pressure to bleed off that rapidly. The pressure drops from about 45 lbs to 0 almost immediately. The car does not run THAT bad after it starts
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Joined: Feb 2007
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From: Woodville Alabama
