so I hooked the test gauge up and ran the car for about 2 minutes pressure was a constant 38-39psi (manual says should be between 34-47) so I went to shut the car off and when I returned to the gauge it was at around 40-41 psi is this normal?? it held at that for right around 30 minutes then it started slowly creeping down. 45 minutes later its at 38-39 psi is this right. should I be worried about leaks or did my car pass the leak test? thanks in advance

 

That's better than most cars.

 

well that's reassuring. im gonna try again see if I get the same results never hurts to check again.

 

The most likely reason that the pressure went back up is due to the fact that the engine oil pressure takes a couple of seconds to taper off after shutdown. The backup oil pressure fuel pump switch is designed to be closed above 15 PSI oil pressure.

The fuel pressure is well within GM spec, which is 20 minutes of holding pressure.