Hello, guys, New to the site, and I just acquired a 91 Firebird 305 tbi. It came with the issue of the fuel pump not wanting to run. The po had wired in a toggle switch to the pump relay and hot wire to get power to the pump so it would run. I found a thread talking about replacing the transistor in the ecm. But, I have to admit, its greek to me. Which one is it in the ecm? And where can I find the replacement transistor, and with what kinda part #? Sorry to be a newb, just not much of an electrical genius. Thanks in advance!

 

You may want to test the output to the relay at the ECM first before assuming its bad. The pin on the ECM that controls the relay is pin A1 (see pinouts below). With the engine running the ECM should provide battery voltage to operate the relay. If it doesent, than its probably easiest to just replace the ECM with another. If battery voltage is present, than it may be the relay itself, or the circuit.

 

Well I tested the Voltage on the pin for the fuel pump driver(dk grn and whitewire) with the car running.It showed 13.8 volts. So obviously it isnt the ecm. I guess the relay is next in line.

 

replaced the relay to no avail. Ended up being the 20 amp fuse at the battery!