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I'm working on a 1988 Camaro with the 2.8l V6 for a disabled veteran. We have a Code 54 for low FP voltage and are experiencing a very extended crank time before it builds enough oil pressure to trip the OP switch that controls the pump. Putting 12v to terminal G on the ALDL causes the pump to run and the car will fire quickly after that. I've replaced the FP Relay and Connector but still no dice. Fuel pressure when running is around 47psi and rises if I rev the engine.
With the Relay unplugged I have 12v constant to the Orange, the ground checks out, jumping the Orange to the Tan cuts the pump on, and I get 12v to the Green/White wire after 2 seconds with the key on and keep this voltage until I turn the key off.. All of the tests in the Chilton Manual check out. HOWEVER, once I plug the relay in, turn the key on, and backprobe the wires, the green/white never gets voltage. If I leave the key on and unplug the relay voltage returns to the green/white. I removed the green/white from the connector, plugged the relay in and applied 12v directly to the terminal and the FP runs.
I'm leaning towards an ECU problem at this point since I can manually work the pump and the relay and both work as they should but I don't want to keep throwing money at it and not fixing the problem. As a last resort I can wire in a momentary push button so he can run the pump for a few seconds before cranking it but the car is super original and I'd hate to have to do that.
The meter only puts a VERY small load on the circuit, I would suspect a blown fuse, or a bad connection somewhere. I can't find the wiring diagram for the relay circuit though..... My service manual isn't laid out as well as I would like.
There is a small transistor that drives the fuel pump relay. It is common for them to go bad. Replace it with a PN2907 and it is good to go again. In the '7302 ECM it is Q6, located in the rear corner by the harness connectors (see picture). It is the one with the small metal tab on it. Note that it may be a full plastic and taller transistor (GM used both styles).
