Car runs want stay started after warms up starts for a second and dies like on 1990 Pontiac Grand Prix

your turning key back off

Asked by for the 1990 Pontiac Grand Prix
Replace the fuel pump relay and see if that fixes it. I had a Pontiac Grand Am that would run good, but if it was turned off after it warmed up, it would not restart for an hour. The problem was a defective fuel pump relay.