1999 Chevy Blazer no power to fuel pump

I have no power to the fuel pump I replaced my relay, and the oil presure switch I have power at the relay and I have power to the gauge side of the connector the fuses are good I have power to the fuelpump side for about 2 seconds after I turn the key off but not when I turn it on I dont have any power at the connector replaced the pump already also I was told the the ignition switch wires could be bad but can prove that because this all started after the truck died and I hit the tank and then I got fuel pressure and then drove it home