1988 GMC S15 Fuel Problem

1988 GMC S15

130,450 MILES • 4 CYL • 2WD • MANUAL

PAPA "G"

MEMBER
2 POSTS

I have fuel at the fuel injector, but when I turn the key it will not activate the injector. I have replaced the injector with a new one, but still does not work. What energizes the injector?

Feb 8, 2009 at 11:30 AM

JDL

✓ASE Certified Mechanic
16,098 POSTS

With the key turned on, is there voltage at the injector plug? The injector is controlled on the ground side by the computer.

With the engine cranking, is there spark at the plugs?

Feb 8, 2009 at 11:40 AM

PAPA "G"

MEMBER
2 POSTS

[quote:75b1649534="jdl123"]With the key turned on, is there voltage at the injector plug? The injector is controlled on the ground side by the computer.

With the engine cranking, is there spark at the plugs?[/quote:75b1649534] Yes I have spark at the plugs, it will burn the gas that has been manually poured into the throttle body. I wonder if it could be the thottle body sensor? I need to know how to test that sensor.

Feb 10, 2009 at 7:59 PM

JDL

✓ASE Certified Mechanic
16,098 POSTS

Hello, in my opinion, you need to test the injector circuits. The injector needs B+ and ground pulse. You can take the connector loose, just turn the key on, The B+ circuit goes hot with the key on, no need to crank, use a test lite on the circuit. If you have B+, then the computer may not be grounding the injector. One reason it may not ground it, is a missing rpm signal.

Feb 11, 2009 at 9:54 AM

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