1994 GMC Sierra Starting

TORNADOCHASER69

MEMBER
1994 GMC SIERRA

Engine Performance problem
1994 GMC Sierra V8 Two Wheel Drive Automatic

We have a GMC Sierra with a 5.7L. Whenever we go to start it there is no fuel initially coming out of the injectors into the throttle body and of course it won't start. However, when we spray a little bit of starting fluid it starts up and continues to run with fuel coming out of the injectors. What causes it to not get fuel at first so it will start on its own?

5 Replies

JDL

MECHANIC
16,098 POSTS

Check the fuel pressure, key on engine off. Should be around 10 psi with TBI. Engine cranking, use a noid lite and check for injector pulse.

Key on or engine cranking, the pump gets battery voltage. Engine running, the pump gets alternator voltage, there is a difference. Right now, I can't tell if problem with pressure, or no injector pulse, at first?

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Tuesday, August 24th, 2010 AT 10:26 PM

TORNADOCHASER69

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3 POSTS

Ok. Sorry it took a while to get back to you. I work two jobs and my main job is 55 miles one way from the house. Anyhow, I did get a chance to test for pulse with a noid light set and didn't get a flash of the light when turning the key on or while cranking.

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Saturday, August 28th, 2010 AT 11:58 PM

JDL

MECHANIC
16,098 POSTS

Is there voltage at the injector plug? If no voltage, check the applicable fuse.

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Sunday, August 29th, 2010 AT 8:33 AM

TORNADOCHASER69

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3 POSTS

There is only voltage when it is running. I even installed a new relay and checked the fuse, which are both located on the passenger side firewall. Could there be something else that is causing me to not get voltage with key on, engine off, or while cranking? It is real frustrating because all I need is that initial fuel prime.

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Monday, September 6th, 2010 AT 9:36 PM

JDL

MECHANIC
16,098 POSTS

The red wire at the injector/s goes hot with the key on, no crank, if it isn't hot, backtrack the circuit. Feed comes from ignition switch. If you losing ignition feed, that doesn't help.