Electrical I Cant Find The Fuel Pump Signal Wire

Zach.T

New Member
Jun 29, 2019
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Florida
iv got a 1995 mustang gt iv done a carb conversion on it with a HEI distributor. i wana use the factory wiring and don't want to hook the fuel pump up to a switch to run all out all the time. theirs a signal wire that goes to the distributor or the TFI to tell the pump how much to pump depending on the RPM i cant find it. theirs a six wire pigtail that went to go to the old distributor i think it might be one of them.
 

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jozsefsz

5 Year Member
Aug 11, 2013
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Cleveland OH Area
It's not an analog signal wire, the PIP informs the ECU that the engine is running based on its RPM. While cranking or running, the fuel pump runs. If it detects the engine has stopped, it shuts down the fuel pump (other than the prime it runs right when you turn over the key). So if you remove the stock distributor and TFI, the ECU no longer knows if the engine's running or not and shuts down. Unless your HEI has an output signal wire that matches what the PIP had output, and you retain the TFI, you won't be able to use this function to keep the fuel pump running.

So you're either into switched mode (run a relay to an switched +12v source) with fuel-pump running continuously with key turned over (no switch required) or you can consider grounding a relay to the oil pressure switch. Once your oil pressure rises, it will run.

Kinda like this: https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/fuel_system_components_and_service/fuel_pump_accessories/parts/12-810

Edit: our fuel pumps also run at constant voltage, no extra juice based on rpm / load. The fuel pressure regulator handles that based on vacuum.

Edit 2: as you're new here I'l also mention you're going to need a fuel pressure regulator back behind that strut tower if you're keeping the stock in-tank fuel pump to bring it down to 4-6psi from the 90+ psi the pump will generate. I have a '78 II and a '69 Montego both running carbs, and I wouldn't trade my EFI for anything, but to each their own.
 
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