1991 Trans Am 305 TPI...Sometimes my fuel pump wont prime or turn on, so my car wont start. Here is what I have tried to fix the problem. New fuel pump (that has been tested good and works sometimes), fuel pump relay, oil pressure switch, and the fuel pump fuse. The sypmtons are:

my car only starts when i hear the fuel pump come on prior to starting.

when my car wont start, I can not hear the fuel pump prime before starting.

Does anyone have any ideas? Could it be my VATS or a short somewhere or what? Thanks for your help.

 

Check your connections and grounding. You may have the connector under the rear seat in your car, so that's another place to look. You can try to monitor voltage at the FP relay when you try to start. If the voltage TO the relay is not present, you can look forward from there. If voltage IS present but the pump does not run, you should look backward from there.

 

I was wondering if you had observed your security light, wich would indicate that your VATS has been activated not allowing you to start your car for the 3 minute time period.