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Re: Need help on 93 c1500 fuel pump won't turn on.
Welcome to the board!
Fuel pump relay wire colors 1993 C/K gasoline engine:
Red (circuit 490) – ALDL connector terminal “G”(for early years) or Test lead
Dark Green with white tracer (circuit465) – From PCM (computer) this controls the relay
Gray (circuit 120) – to fuel pump - earlier TBI trucks had tan with white tracer
Black with white tracer (circuit 450) – Ground – to engine ground G109 (by T-stat)
Orange (circuit 440) – power from fusible link at firewall junction block
The ECM controls the fuel pump relay.
The truck has a fuel pump relay that supplies power to the fuel pump when:
- Anytime the ECM receives a distributor reference pulse. (Engine running / engine cranking)
- The key is turned on engine not cranking – relay applied for 2 to 20 seconds.
When the engine has oil pressure a redundant circuit supplies power to the fuel pump. This circuit goes through an oil pressure sensor/sender. This circuit is independent of the fuel pump relay.
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For those of you that are wondering why you are not getting replies to your thread:
Did you give the model, year, engine, fuel system type, and transmission information?
If it is modified from what came stock from the factory, let us know that too.
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