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Old 12-22-2012, 03:20 PM
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Originally Posted by 1939P7 View Post
I'm not sure if you have the oil pressure switch that is hooked up to the fuel system.. I couldn't load the the pic here but will post it in my photo's
There should be an oil pressure switch, but that is unlikely to be the problem. The TBI system uses the oil pressure switch in parallel with the relay. The computer energizes the relay to operate the pump for about two seconds when you turn the key to START. This provides pressure to the TBI injectors before the oil pressure rises enough to close the oil pressure switch. Once the engine is cranking, the oil pressure switch closes, bypasses the now open relay, and provides current to the fuel pump.

Now, are you testing the system correctly? There should be +12V at the relay feed, but you WON'T get anything to the pump unless either you just turned the key to START (that two second timer) OR you have oil pressure that closed the switch. The only way to test the pump and wiring is to remove the relay and temporarily jumper across the two pump contacts in the relay socket. If the pump turns on, the circuit is working. If not, use a test light to trace the wire from the relay connector to the tank. The selector switch is a likely candidate, as are all the connectors in the harness. If you now get 12V at the tank, check the pump and ground wire at each tank.
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