Wife has owned her 91 Firebird for 25 years; what a car it has been.


Have fixed a lot of problems (including replacing fuel pump last month) but this is the first problem that has stumped me. Have been diagnosing and testing for past three nights and have read hundreds of posts on this site. Decided to post this before buying anything more.


Replaced fuel pump last month; no problems and ran well until this week and it just died on the road. Cranks but no start; will run a few seconds on starting fluid. Getting Code 54; no other codes. Has spark at plugs; main fuel pump fuse good and 12V power to fuel pump relay (but I replaced relay anyway thinking that had to be the problem); fuel injector fuses good and I have power to one side of both fuel injectors connections; ohm check of resistor posts was 15; fuel strong to throttle body connection and runs out when I loosen nut and jump fuel pump; have not checked line pressure. Security Light goes off after switch turned on so I don't think it is VATS.


Just read about ignition control module so I haven't checked for power at that connection. Since I have spark, not sure it is relevant.


Also have not done anything with oil pressure switch because my read of posts says if you have fuel prime, it should start and run for a few seconds and then die if the OPS is not working.


Issues so far that seem to be problems:
1. No power to green/white wire at fuel pump relay when switch turned on (signal from ECM to power fuel pump relay).
2. When cranking, injectors so not seem to be pulsing fuel.




Does anyone think it is the ECM? I live a long ways from a parts store so any help would be appreciated. Thanks.

 

What is code 54?

You should have power to BOTH sides of the injectors until the ECM supplies ground to the circuit. Then you'll have power to one side, and pulsing power or reduced power to the other side. The ECM pulses the ground connection to turn the injectors on and off.

I don't know what an "ohm check of resistor posts" means.


If the fuel pump works during ignition-on prime, then the fuel pump relay is working. If the fuel pump relay works, you don't need the oil pressure switch-to-fuel pump circuit at all. The oil pressure pass-through for the fuel pump is the backup to the fuel pump relay.


You shouldn't have power there except during prime and when the ECM is getting a crank signal from the distributor.
Yep, that's a problem.

Entirely possible. I'd be looking to see if the ECM has the injectors perpetually "on" instead of pulsing them. I'd check to see if the fuel pump relay is being turned on when the engine is cranking.

 

Here's a good place to start

 

Pulled this image of code 54 from my copy of the pdf '88 Firebird service manual. Compared it to the my '91 Firebird service manual and it is the exact same thing with the exception of the engine model captions. That being said. If you are getting a prime of the fuel pump, clear the code 54 and see if it comes back when cranking the engine. If it does then you may be looking at a faulty connection at the ECM, a faulty ECM, or an open circuit 120 to the ECM. Good luck.

 

Replaced ECM. Fuel Pump Relay now clicks and Code 54 disappeared but still won't start and still don't have power to the blue and green wire sides of each injector harness. Guess I now need to go back to see if I still have spark.

 

Check EFI fuse...