Mechanics

FUEL PRESSURE REGULATOR

GMC C1500

I have a '97 GMC 1500 2wd 5.0 ltr. Auto.
Installed a new fuel pump last week. Engine died today under normal running conditions. Fuel pump is operating. Engine won't start unless gas is added manually.
I suspect the culprit is the fuel pressure regulator, but would like confirmation.

Thanks in advance,
Hook1
Avatar
Hook1
August 27, 2007.




I forgot to mention the above truck has 155,000 miles.

Thanks,
Hook1

Tiny
Hook1
Aug 27, 2007.
When you turn key On-do you hear the fuel pump come On for a few secs?

Tiny
Rasmataz
Aug 27, 2007.
Yes, The fuel pump does run, I can hear it running.

Thanks,
Hook1
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Tiny
Hook1
Aug 27, 2007.
Don't feed it-crank engine over is the injector/s clicking listen to it real close.

If you can hear it clicking-check the actual fuel pressure with a gauge.

Tiny
Rasmataz
Aug 27, 2007.
I replaced the fuel filter today, and I have a new regulator.

I do hear the injectors clicking.

I don't have a fuel pressure gauge.

I'd like to make sure the signals are being delivered to the injectors. Would they be clicking if there wasn't a signal being sent?

Hook1

Tiny
Hook1
Aug 28, 2007.
If you can hear it clicking it means its pulsing-could be the injector/s is clogged up or no fuel pressure even if you hear the pump. Could be your oil pressure sending unit this the one that powers it after the fuel pump relay does its thing.

Tiny
Rasmataz
Aug 28, 2007.
I'm not sure I understand how the oil pressure sending unit affects the fuel flow situation. Can you provide more information.

Thanks for all the help,
Hook1

Tiny
Hook1
Aug 28, 2007.
The PCM monitors oil pressure, if the computer senses no oil pressure it cuts off the injectors (to save the engine from a siezure). This can stall an engine at low idle, normally at higher RPM's the oil pressure is high enough to keep the computer happy.

I used an old guage off a tire foot-pump. Hooked it to some fuel line, then attached that to the engine side of the fuel filter and turned the key to ON (but not start) and see what pressure shows. You need to put circular clamps on each end of the hose as the pressure can get right up there and you don't want gas spraying all over.

Tiny
Rmchambers
Aug 28, 2007.
Mr Hook1 this is how it goes

Oil sending unit /Fuel pump circuitry:


http://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_4.gif


Tiny
Rasmataz
Aug 29, 2007.
First of all, thanks for all the help!

Checked the fuel preesure and found that it went to 35 lbs. When I turned the key to the on position, but immediately dropped to zero. Decided it might have had a faulty check valve. Replaced the fuel pump and the engine starts now.

I replaced the FPR and the Oil pressure sending unit, to no avail.

My question is this: Could a faulty fuel pressure regulator cause a new fuel pump to go bad, or burn out?

Hook1

Tiny
Hook1
Sep 28, 2007.

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