[kalbert]

The pump should be on a relay and the relay should be energized when the key is in the crank position, or the key is in the run position and there is oil pressure. Having the relay turn the pump on when the key is in the crank position ensures the fuel system is priming when you're cranking. Having the relay turn the pump on when they key is in the run position and there is oil pressure ensures that the pump won't run if the motor isn't.