The fuel pump mystery

1997 Chev Suburban with 117,000 miles. Was running good until won’t start one day. Towed to mechanic; new fuel pump. Ran good for 24 hrs, then wouldn’t start. Back to mechanic; replace the fuel pump. Ran good for 48 hrs: then, again, wouldn’t start. Back to mechanic again. Both fuel pumps were GM parts. What is happening? Is it possible to have 2 new fuel pumps fail?

Maybe bad wiring, connector or relay to the fuel pump? Try measuring voltage to pump when it’s not working. Use an insulation piercing probe (or a safety pin) to check the wires going into the pump.

Yep. I don’t know what’s going on with the AC pumps but I’ve had problems too. Either made in Mexico or China. A few years ago I went through three of them in a row before I got a good one. This year I had a new one put in and next day started having trouble. The replacement has been fine.

On the other hand, you have to replace the wiring harness inside the tank too. Double double check the connectors and wiring, and some people recommend replacing both the relay and the oil sender/relay when a pump fails because of the stress a failing pump puts on those parts.