a couple months back i was doing 90 mph down the highway when my car started to act up it started to loose oil pressure then it lost all oil pressure and i pulled over and got it towed home so i just pulled the motor and replaced the oil pump and put it back in and the car will start up but as soon as i let go of the ignition it shuts off . the fuel pump does not prime i can not hear it. the inertia switch is good it is pressed down so what else could it be