Community Q&A Question: WOT relay/fuel pump

Asking About: Mustang Standard WOT Shut Off/Fuel Pump Relay (86-92) 5.0


WOT relay/fuel pump

I got an 88 mustang GT. I was having problems with it and my pump didnt wanna prime. My relay under my saet had power and the relay on the side panal on passanger side too. My inertia switch wasnt getting any power so we used a jump wire to trick the new fuel pump and it works. Question is. Would the WOT relay have anything to do with no power to the inertia switch and not letting the pump prime?
from McAllen |

Accepted Answer
No sir, the WOT relay is for the A/C compressor clutch and what it does is turn off the A/C compressor at wide open throttle. If your under-seat fuel pump relay is indeed functioning properly, then you have a wiring open between the relay and the inertia switch.
from Hewitt |

So what relay is suppose to click when you turn the key to the on position? I thought it would be the WOT relay since it was by the CAI - Daniel 3 years ago

And that relay was the one that was clicking - Daniel 3 years ago

Your Fuel pump relay is located under the seat. The PCM closes it briefly on key-on to prime the pump and then full time once the engine is running. The WOT relay clicking is part of the PCM prove out on key cycle - Jonathan 3 years ago

With the key on, you should have 12 volts at the solid red wire and at the Black with orange tracer wire. These are input voltage. During key on pump prime and key on engine running, you should have 12v at the pink with black tracer wire, That is the output voltage to the fuel pump. - Jonathan 3 years ago

If i dont get a reading would that cause my car not to start? - Daniel 3 years ago

Yes. If you dont have 12v at the wires I called out at the times I called out, that means one of the following - blown fuse, bad relay, open wiring. - Jonathan 3 years ago

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Question About

  • Mustang Standard WOT Shut Off/Fuel Pump Relay (86-92) 5.0
    Standard WOT Shut Off/Fuel Pump Relay (86-92) 5.0
    This item is no longer available.