Originally Posted by Bungle

I have something similar to this on my 02 Z28:

Leave car overnight - car fires first time
Drive car and then switch off, try to start after 30secs - car fires first time
Leave the car for 10 min or even a few hours - car cranks but will not start, turn ignition off and after a few second try to start and the car fires first time

Have changed the regulator on the fuel rail and no change.
Changed the starter motor and no change
Have tried swapping the ignition relay and no change
Changed the battery and no change

At a loss now but guess i am left with the fuel pump or possibly VATS? Any advice welcomed!