GMC Fuel Pump

HUGH IN LOUISVILLE

MEMBER
1999 GMC SONOMA
4 CYL
2WD
AUTOMATIC
200,000 MILES

I have a '99 GMC Sonoma. It quit running, and we replaced the fule pump. Could not hear the old pump running, The new one isn't running either, and the relay is ok.

What to check next?

tia

Monday, February 21st, 2011 AT 7:55 PM

7 Replies

JDL

MECHANIC
16,098 POSTS

Did you check for voltage and ground at the fuel pump connector? Engine cranking, use a voltage tester, gray wire is voltage black is ground. In the diagram, check the fuse circuit for voltage.

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Monday, February 21st, 2011 AT 8:03 PM

HUGH IN LOUISVILLE

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Thanks JDL, I'll check that and see. Raining here, so it may be a few hours before I know.

Appreciate the quick reply !

Hugh

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Monday, February 21st, 2011 AT 8:09 PM

JDL

MECHANIC
16,098 POSTS

I hear you, hard to work on them, outside in nasty weather.

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Monday, February 21st, 2011 AT 8:24 PM

HUGH IN LOUISVILLE

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JDL, It was indeed the ground. We worked on it outside on the curb and I had disconnected the tail lights in order to lift the bed and scoot it back enough to get to the pump. There was a ground lug/eyelet connected to the wiring on the driver side tail lights I had un-bolted from the frame.

I took a harder look at the pump wiring and saw that there was some wiring running inside the frame going to the rear of the vehicle. That was the problem, we hadn't re-grounded that eyelet to the frame. We had tested for current initially, but not the ground.

All is well now, and it's running fine.

Thanks again friend !

Hugh

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Wednesday, February 23rd, 2011 AT 12:34 AM

JDL