I have Issues with my Uncle's 92 Firebird. It has a TBI 305, with 264K on the clock. We've replaced the Fuel pump, Relays, and the damn thing still doesn't work. There is no Fuse in the Fuse box for the Fuel pump. There is no Inertia Switch like in the Fords Either. I can't think what the hell is going on. PLEASE HELP!!! Thanks in advance!

 

By "doesn't work", am I correct in the assumption that the fuel system isn't working. i.e. the system isn't priming, no go, nothing? If so, check the fuel pump relay/ECM memory fuse located up towards the front, Camaro's are near the battery/overflow tank, I THINK the birds were near the radiator support...small inline weatherpack fuse. If this blows, the fuel system is dead.

 

Check your wireing with a DVOM

 

Try the Oil Pressure Sending Unit - should be just above the oil filter on your 1992 TBI motor.

The fuel pump is wired directly from the battery through the OPSU - and a bad OPSU can do all kinds of things. Mine went bad, and made my pump run constantly, even with the key off and in my pocket, the FP ran all night and killed my battery several times until I traced it down. $28 at Autozone to replace.

 

An oil pressure switch is wired in parallel, not in series, with the fuel pump relay. Judging by the posters descriptions, it sounds as if it isn't working. The oil pressure switch has no effect on the fuel systems initial run sequence.

 

All I know is that on a TBI car, the FP gets direct current through the OPSU from the battery, regardless of ANYTHING ELSE - including the key and whether it's even in the car - thus why my FP drained my battery dead over the course of 2 days with the key in my pocket the whole time, and the key not even seeing the car during those days at all (I finally heard the pump running one night at 3am when all was quiet - and thus I knew why my battery was dead).

It stands to reason then - that if the OPSU can allow constant current to the FP regardless of key position, then the OPSU could also fail in a manner as to not allow the FP any current at all, regardless of key position.

I'd say check Haynes or Chiltons, but neither has a wiring diagram for the fuel systems on a TBI car.

If nothing else it's a simple 5 minute, $28 test to help diagnose.