ps374

On my 1984 I would like to eliminate the alarm systen .For years I have had a intermittent no start condition. All the distributor compontents and sensors have been changed or tested. I believe it is in the alarm system which shuts off fuel from the engine. Will removing the relay behind dash cause the horn to stop working? Any information helpful.

flannel_man

Well for one you don't have to touch the relay. Just unplug the 10 amp fuse behind the DIC. The horn will still work on the steering wheel.

If the fuel pump doesn't run more than 2 seconds to prime it for startup look at oil pressure. The fuel pump won't run if the PCM doesn't see oil pressure

ps374

Thanks for the great infomation

flannel_man

When you turn the ignition On, the ECM will energize the fuel pump relay by providing 12 volts on Pin C Dark Green/White wire for 2 seconds. The fuel pump should run for 2 seconds.

If the engine is cranking or running the ECM will continue to provide 12 volts to Pin C Dark Green/white wire and the fuel pump should run.

If the engine oil pressure exceeds 4 psi, the oil pressure switch closes and 12 volts from an Orange wire goes to the fuel pump fuse and the fuel pump should run as long as the oil pressure is above 4 psi. This is a backup mode in case the fuel pump relay fails. An indication the relay has failed is long crank time before the engine starts.

Another way to test the fuel pump motor is with the ignition OFF is to use a 10 amp fused jumper wire and apply 12 volts to Pin G of the diagnostic connector. The fuel pump should run all the time. Or to test the fuel pump directly use a fused 10 amp jumper wire and apply 12 volts direct to the fuel pump fuse. If the fuel pump doesn't run the pump or wiring to the pump is bad.



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