Sounds like you have the wrong sending unit, it had two terminals reversed when it was made, or the plug is in backwards.
GM had some systems that ran the fuel pump off a terminal on the sending unit as a safety cutout. If the vehicle was in a crash that ruptured a fuel line, there would be no fuel pressure so the engine would stall. When it stalled, there would be no oil pressure so the switch in the sending unit would turn off and turn off the fuel pump. That would stop it from pumping raw fuel onto the ground.
Tuesday, May 3rd, 2011 AT 5:46 AM