Mechanics

GMC SONOMA FUEL PRESSURE PROBLEM

2003 GMC Sonoma • 120,000 miles

I have a 2003 Gmc Sonoma, 4.3. The engine will crank over, but will not start. I have poured gas down the throttle body and it starts. So I do have spark. I have connected the the scan tool to the OBC, and there is no code for a problem. I did a fuel pressure test and with the key on it is 60 psi for two seconds until the pump shuts off. Then it drops to 58 psi. Within 5 minutes the pressure drops to 54 psi and holds. I have checked voltage to all the sensors and fuse box. I'm getting correct voltage. I recently remove the Plenum intake cover and performed a visual test for the injectors. All six injectors are working. I'm thinking maybe a fuel pressure regulator? I didn't see any leaks from the regulator. Any Ideas? Thanks!
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Lasurvivor47
January 3, 2013.



How do you know the injectors are working ok? How did you test?

The crank sensor controls injector toggle. It should have coded if bad,

you removed the plenum? Re check the connector for the injector spider assembly.

Roy

Thanks for your reply. How I tested the spider was, I disconnected the coil and removed one injector at a time. I had someone crank the engine as I watched the injector spray. I used a small jar to catch the gas as it came out. All the injectors worked the same way. Now whether there was enough pressure coming out of the injectors I'm not sure. I did have good fuel pressure when I used the fuel gauge tester to test the system.
No bad codes came up when I plugged the scan tool in. I checked it a few times.
I tested the connector going to the spider. I had power. Thanks Roy! Paul

Tiny
Lasurvivor47
Jan 3, 2013.
I just tested the crankshaft for voltage. At the battery it's 11.75 volts and 10.45 volts at the crankshaft sensor connector. I also tested for voltage at the spider connector. All six pink wires had 11.75 volts. Thanks. Paul

Tiny
Lasurvivor47
Jan 3, 2013.