Low Voltage to Fuel pump

[L31MaxExpress]

I put a Racetronix harness on both the Express and Tahoe for this very reason. Forget the OE wiring, grab a Racetronix harness and be done with all the foolishness trying to make the under spec OE wiring work 25+ years later. My OE pumps were barely getting 10 volts with a harness that was in perfect condition and good relays. Pump gets within 0.2 volts of the alternators output stud with the Racetronix setup.

 

[rdldrdld]

Thanks everyone. I think we have it. We have 11.5 v at the pump on the gray, which the service dealer verified was the correct wire. We may have had a faulty battery and/or alternator. The battery tested bad at O'reillys. We noticed the incorrect pulley on the alternator, so in the interest of time we just replaced the whole unit. The ground and power seem to test OK.

 

[rdldrdld]

Thanks everyone. I think we have it. We have 11.5 v at the pump on the gray, which the service dealer verified was the correct wire. We may have had a faulty battery and/or alternator. The battery tested bad at O'reillys. We noticed the incorrect pulley on the alternator, so in the interest of time we just replaced the whole unit. The ground and power seem to test OK.

I will refer back to these comments if the fuel pump goes out again.