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So I installed an electronic fuel pump on an 82 F100. I tried to find a wire that I thought would be hot at all times when the key was on but it did not work. I tried the positive wire to the coil but that did not seem to work. I tried the oil pressure gauge wire as well. Can any one suggest another wire I can splice into that will give me current when the key is on?
There are really none under the hood. How much current does the pump draw? If it draws over 5 amps, I would use a relay. I would use a fuse tap and tap into the fuse box to a circuit that is hot with the key on, such as the wipers or the blower. It would be nice to find a circuit that was not hot when in accessory, so you could listen to the radio without the fuel pump running.
I would then run this wire out through the firewall to a Bosch type foglamp relay mounted near the starter solenoid on the fender. I would then run a wire off the battery + with a fuse to the relay, and then out of the relay to the fuel pump.
i would also put an inline inertia switch,or put a tee fitting where your oil pressure switch,and put another pressure switch in so if the engine is not running your pump is not running. just incase somebody hits you in an accident,your pump isnot pumping fuel causing a fire hazzard.ford had these systems on 85-86 trucks with intank pumps.