Quote:
Originally Posted by Trio3b
Will check fuel pump connections positive and ground visually.
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Pointless. Connections can "look" good yet have high-resistance.
Verify voltage as close to the fuel pump as practical (typically at the rearmost connector before the harness goes "up and over" the fuel tank.) The fuel pump must be RUNNING, so do this with the engine running. GM uses undersized wire, so ~2 volts less than alternator voltage is probably acceptable.
Check for voltage on the ground wire as close to the fuel pump as practical. Again, the pump must be RUNNING. Same undersized wire, (but not as much of it) so ~1 volt is probably acceptable.
With two volts of loss on the positive side, and one volt of loss on the ground, the fuel pump will be running on ~11.x volts when the alternator is charging at 14.x volts. Sux, but that's GM's wiring harness. At 11 volts or less, you have wire harness problems.