Not the same vehicle, not the same year...but...I have a '92 and a '93 Lumina. I was checking fuel pump voltage and current draw prior to replacing the fuel pump on the '92.
I discovered that GM had used under-sized wire for the entire fuel pump power circuit. Everywhere I tested I was finding another couple of tenths of a volt of voltage drop--a total of about 1.5 volts on the + side, and about a volt on the ground side.
With the engine off, and the battery at 12.6V, I had about 10.1 volts actually powering the fuel pump.
I then tested the 93, and got exactly the same results.
First Guess: 12.6 volts at the battery, 10 volts at the pump, 2.5 volts of voltage drop is TOTALLY NORMAL. GM saved thirteen cents by using 16 gauge wire instead of 12 gauge in the fuel pump circuit.
I discovered that GM had used under-sized wire for the entire fuel pump power circuit. Everywhere I tested I was finding another couple of tenths of a volt of voltage drop--a total of about 1.5 volts on the + side, and about a volt on the ground side.
With the engine off, and the battery at 12.6V, I had about 10.1 volts actually powering the fuel pump.
I then tested the 93, and got exactly the same results.
First Guess: 12.6 volts at the battery, 10 volts at the pump, 2.5 volts of voltage drop is TOTALLY NORMAL. GM saved thirteen cents by using 16 gauge wire instead of 12 gauge in the fuel pump circuit.
