91 camaro No power to fuel pump


Old 01-31-10, 11:23 AM
Thread Starter
Join Date: Jan 2010
Location: illinois
Posts: 1
91 camaro No power to fuel pump

Ok here's where we are at. No fuel pump signal to the relay while starting. 10.8v between the orange and gray wires on the FP relay connector when ignition switch is in the on or off position but no start. If I jump gray wire at connector with known good 12v supply the FP runs and car starts. When I measure volts between Orange and gray wire with the car running I get 12v. Disconnected the OPSU, 3 wire, red,yellow,black, and tried to start. Nothing. Jumped and measured voltage at red and black wires at OPSU (2.4v) and nothing. Relay is good. FP fuse is good. Where should I look next? Seems like I am not getting a signal to prime the FP.
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Old 01-31-10, 11:46 AM
Join Date: Oct 2008
Posts: 1,312
I would not even try to troubleshoot that problem without a factory electrical diagrams manual and a multimeter.

The factory electrical diagrams manual would be part of the factory service manual set (4 books and up to 2000 pages total) which you can order from a dealer or helminc.com

For every vehicle I troubleshoot electrical problems on, there are different colored wires and different circuits. Even the same manufacturer, same vehicle, but different year -> same exact part - they go and change the wire colors, the electrical connector, and sometimes how the gizmo operates electrically!

Anyway the factory service manual set will have complete troubleshooting instructions for this problem along with the *complete* wiring diagrams for the vehicle.

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