2001 Fuel Pump Electrical Circuit

My wife calls me and says the Bravada won't start. Turns over vigorously but sounds like it's out of gas. The tank is 3/4 full. She calls back 20 minutes later and says it starts but runs "odd". I tell her to take the car home and I'll take a look at it.

When I get home, I turn the ignition on and listen for the fuel pump. Sounds normal, so I turn it over and it starts right up. I turned the car off and did the same thing twice more. On the third start, the car just shut off about 5 seconds after start. On fourth try, I didn't hear the fuel pump. I haven't heard run it since.

So I check the ECM/fuel pump fuse - looks good. Swaped the horn relay with the fuel pump relay (they're identical). Horn still works so it must not be the relay. I dropped the fuel tank and replaced the fuel pump assembly (not fun at all :shakehead ). I'm pretty sure hoses and electrical connections were reconnected properly and are undamaged.

I even charged the battery but I don't have fuel pump operation (no noise, no pressure). What now?

check the gray wire at the fuel pump connector.. should read 12v with KOEO (key on engine off) for 2 secs- are connectors burnt?, melted?, good ground? New fuel pump - is it aftermarket?- or an OEM replacement pump? Did you have to splice in any wires? Has new pump ever ran- did you bench check it first?

I ran a bypass to the pump using straight battery power. Pump worked. Then I did a continuity check of the ground wire to the pump and then the positive. Both checked out OK. So I hooked everything back up and started the car. No problems since.

The only thing I can figure that I did wrong is that I seated the connector just enough to complete the sending unit/fuel gauge circuit but not enough to get juice (or ground) to the pump.

Thanks for the update, hope it's fixed for the next several years.