Fuel pump will not prime

1999 GMC SUBURBAN
200,000 MILES • V8 • 4WD
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TYLER WOODS
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Fuel pump relay checks fine, fuse is good. Engine runs fine if I manually prime the throttle body with a dribble of gas but the pump won't run before the engine starts. My manual doesn't show details of the primping ckt.
Aug 28, 2019 at 1:54 PM
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ASEMASTER6371
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Good afternoon,

The two second prime comes from the PCM. It is sent to the fuel pump through the relay and the module on the left front frame rail.

I attached a wiring diagram of the pump for you to view.

Roy
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Aug 28, 2019 at 2:09 PM
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TYLER WOODS
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So my problem must be between the relay and the PCM (or the PCM itself) since the vehicle runs well once started. Thanks.
Aug 29, 2019 at 7:26 AM
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ASEMASTER6371
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That is correct. My bet is the PCM.

Roy
Aug 29, 2019 at 8:28 AM