86 Mustang 5.0 Fuel Pump Cut Off Switch

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by jrcg92, Jan 13, 2014.

  1. jrcg92

    jrcg92 Member

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    Hey everyone, im a little new here. Im the new owner of a 86 5.0 gt and I want some security when it comes to my car. ultimately, i want to run a few kill switches in my car to make it theft proof and i want to start off with a fuel pump cut off. i know the relay is under my drivers seat. but to be completely honest, im blind on how to wire things together as far as the switch goes and which pin i actually wire everything to. so im looking for the help so i dont mess this up.

    Also, the switch i have is a dual switch, so i have 2 i can use, also want to run a starter kill as well.
    thank you in advance.
     
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  2. f8tlfiveo

    f8tlfiveo My wife likes my spool and blow-off valve.

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    I think there is a cutoff switch in the back of the car for the fuel pump. Pretty sure it is just a reset if you flip the car or get into an accident. Should be behind the plastic around the tail lights
     
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  3. jrcg92

    jrcg92 Member

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    That's the inertia switch. I know that the relay is under the drivers seat. But I got this figured out now since I did more research on it. Thanks for the help
     
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  4. 84Ttop

    84Ttop They make new pistons every day, so why worry?
    SN Certified Technician Mod Dude

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    I would just add a switch to the ground leg on the relay to use it as an interrupter. Same goes for the starter relay. You could just add a switch to interrupt the signal to the starter relay. Personally I find it easier to just pop the dist cap and put the rotor in my pocket if I'm really worried about it.
     
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  5. jrichker

    jrichker StangNet's favorite TOOL
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    Follow this tech note for the best way to wire a fuel pump kill or anti-theft switch...

    On 86- 91 cars the fuel pump relay is under the driver’s seat, 92 and later cars, the fuel pump relay is under the Mass air duct on the passenger fender well.

    Note that the wire colors changed in 1991, so there are two different descriptions.

    86-90 model cars:
    Cut the red/black wire going to the fuel pump relay. Splice a 16 or 18 gauge wire into the wire and connect it to one side of the switch. Connect the other side of the switch to the other end of the red/black wire going to the fuel pump relay. When you are done the switch should be in the middle of the spliced red/black wire that goes to and comes from the fuel pump relay. Using the control side of the circuit allows you to use light gauge wire and light duty switches. There is less than 1 amp going through the circuit, so you don’t have to worry about voltage drop across the wiring depriving the fuel pump of electrical power.

    [​IMG]

    91-93 model cars:
    Cut the Lt Blue/Orange wire going to the fuel pump relay. Splice a 16 or 18 gauge wire into the wire and connect it to one side of the switch. Connect the other side of the switch to the other end of the Lt Blue/Orange wire going to the fuel pump relay. When you are done the switch should be in the middle of the spliced Lt Blue/Orange wire that goes to and comes from the fuel pump relay. Using the control side of the circuit allows you to use light gauge wire and light duty switches. There is less than 1 amp going through the circuit, so you don’t have to worry about voltage drop across the wiring depriving the fuel pump of electrical power.
     
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  6. jrcg92

    jrcg92 Member

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    Right on. Getting more help here than a lot of other forums.
     
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