I have a '96 Bonneville SE 3800 with a challenging electrical problem.

It started when the car died while driving. After some testing we determined that the fuel pump was bad so it was replaced. That didn't fix it. So time to investigate. This is what I found. When I disconnect the SU (sending unit) and measure the voltage back to the e-conn I get battery voltage until the relay takes it to zero after a few seconds. I then operate the pump on a bench power supply and it works good. I put them together and they don't work. I looked at the e-conn'* and they look fine. I measured the resistance of the SU wire harness and this is what I found + 0.6 Ohms/ - 0.7 Ohms. This seems fine but not sure of specification. I also measure the resistance of the negative lead on the e-conn (from the e-conn to the negative battery terminal) and got 24 Ohms.

I am stumped.

Any suggestions would be greatly appreciated.
Cory

Give this a try. Symptoms are pointing to this. Let us know what you find.

Ground Bus

Thanks for the help. This was it. Corrosion wasn't the problem though. The plastic e-conn melted on the thickest connector which is I think the wire that either goes to the neg battery or the vehicle was causing a bad connection. I am guessing to much current was trying to go through their and heated up the connection and melted the plastic. After cleaning up the terminal and applying dielectric grease and reassembling the other electrical problems were fixed and the pump now runs when it is supposed too.

Thanks a million. You saved me a lot of time looking at the wires and e-conn'* between the pump and where ever they originate.