Circuit Opening Relay Wiring
Circuit Opening Relay
A circuit opening relay can be used to run a electronic fuel pump in an EFI car. The circuit opening relay provides power to the fuel pump while cranking and keeps running when the engine starts up (Provided your ECU has a place you can wire it to). I have used a circuit opening relay in my AE86 4AGE wired to the "FC" pin on the ECU.
If the engine is running an AFM then the same relay can be used, but the green wire needs to be connected to the AFM. There are two pins you need to find on the AFM (usually both are at one end of the plug) these pins are connected when the AFM flap is open at all, and disconnected if the AFM flap is completely closed. Connect one pin to earth and the other to the green wire out of the relay.
Wiring Diagram:
White/Black - Wires to to STA - Starter/ECU Start Signal.
White/Red - Wires to EFI Relay - +12v Ignition Switched power (Run through a suitably sized fuse, 10A is usually fine, but depends on your fuel pump).
Green - Wires to engine run signal - "FC" pin on 4AGE ECU. Or if you are running an AFM engine, this wire should connect to the AFM.
Black - Wires to body earth - Wire to closest earth point.
Blue/Black - Wire to fuel pump positive - Gives power to your fuel pump.
Article by Medicine_Man
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