Hi all.

so I think this is what's happening with my 91 V6 Firebird. On Sunday last week the car decided to not start. Or to be more precise it starts but runs for 2 seconds and dies.

I tried a few times and it's always exactly the same so it's getting fuel and spark but it's as if once the engine starts the power to the fuel pump is cut so it's just firing on the fuel that's been fed to the rail when the pump primes?

and I've got no idea where to start on this one! Any help greatly appreciated

 

First thing to do is to check the in-line fuse,... should be mounted body next to the Charcoal canister ( or battery depending on car. )

* COULD be* the oil pressure / fuel pump switch. I don't know specifics about the 91 Firebird V6 but fuel injected cars used a oil pressure switch to cut power to the fuel pump when the engine shuts off ( 0 oil pressure ) so the fuel pump would not continue to run. If that switch isn't working than I assume the car would start using the pressure built up during the "pump prime',... but the fuel pump isn't running after that because the oil pressure cut off isn't working ( *thinks* there's 0 oil pressure so not allowing voltage to pump. ).

Best advise Is to find the 91 V6 wiring schematics for the fuel pump and start probing the '+' wiring at the pump, pump relay and oil pressure cut-off to find out if/when the fuel pump is shutting down. ( simple test light works, voltmeter is better. ) You can also connect a fuel pressure gauge to the fuel rail to verify exactly when the fuel pressure drop begins.

This diagram is for the 91 Camaro; 91 Firebird *might* be different

 

Thanks man. the oil pressure switch possibly? Hmmm I never knew that about it cutting power to the fuel pump