Mechanics

GMC SONOMA FUEL PRESSURE PROBLEM

2003 GMC Sonoma • 120,000 miles

My 2003 gmc sonoma 4.3 will crank over, but will not start. If I add fuel down the throttle body it will start and then shut off after the fuel is used up. I know I have spark. I cleaned the IAC and the map sensor. I also did a fuel pressure test. The results were 58 psi with ignition on and around 57 psi cranking. When I stopped cranking the engine the pressure stayed at 57 psi for more than 5 minutes. I'm thinking either a leaky fuel regulator, or fuel injectors, or even a vaccume leak? What do you think? Thank you in advance! Paul
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Lasurvivor47
December 27, 2012.




I'd use a noid lite and check for injector pulse, engine cranking. The autostore sells a noid lite. Check for voltage at the injectors, key on, pink wire. That circuit is fuse protected.

JDL
Dec 27, 2012.
Ok thank you I will try that. I appreciate your time!

Tiny
Lasurvivor47
Dec 27, 2012.
No problem. Let us know what you find.

JDL
Dec 27, 2012.
I used my test light to check for voltage to the spider connector. There are 7 pink wires and all have power. I had someone crank the engine while I tested for a pulse on each wire. I got a pulse for each wire. The noid light doesn't connect to the spider connector. I could smell alot of fuel! I'm thinking fuel regulator is leaking? Thanks!

Tiny
Lasurvivor47
Dec 27, 2012.
I thought your fuel pressure looked good. Any applicable trouble codes? Check the coolant temp sensor.

Part of the fuel pressure test is to bleed pressure down to 10 psi, monitor the fuel gage for 5 minutes. If pressure drops more than 2 psi, replace the pressure regulator.

JDL
Dec 27, 2012.
I don't have a scan tool. So I can't check the codes. Can't afford a scan tool right now. I will check the coolant sensor. When I had the fuel pressure tester connected and stopped cranking. The pressure remained at 57 psi and didn't drop. Thanks again!
AD

Tiny
Lasurvivor47
Dec 27, 2012.
Usually, obd2 code readers don't cost much? I understand money issues. I have the same problem.

JDL
Dec 27, 2012.
Ok my friend I will check that reader out. Thanks!

Tiny
Lasurvivor47
Dec 27, 2012.
Let us know what you find.

JDL
Jan 8, 2013.
I bought the code reader and no codes came up. I re checked the fuel pressure and it was below 50 psi. The first test was higher. So I'm going to change the fuel pump and filter. Thanks for getting back to me. Paul

Tiny
Lasurvivor47
Jan 8, 2013.

AD