Extra Security: Fuel Pump Cut Off Switch

The idea is to install a switch in the power circuit to the fuel pump, with the switch hidden in a secure spot. With the switch off and fuel pump dead, the engine quickly dies. Car cranks like usual, but doesn’t run for more than 5 seconds. The only way to steal your car now is to tow it or put it on a trailer.

You will need the following parts for the mod:
Wire cutters and striper
10 ft. of 12 gauge wire or one size smaller (length depends on where you put the switch)
Exacto knife or razor blades
Shrink tube insulation or electricians tape (shrink wrap/tubes better – from Radio Shack)
Soldering gun and solder
A bunch of male/female connectors
A switch (two pole). I got a rocker switch from Radio Shack that was rated for automotive use.

Here’s the creative part. Find a location for hiding the switch. I’d tell you where I put mine, but then I’d have to kill ya. However, here are some suggestions. Under the shift boot, you press through the boot cover to hit the switch. You might have to do some fabrication of a switch holder bracket; in the ashtray/cigarette lighter area; inside the console compartment (too obvious); inside the trunk of the car (pain to get to, but max hidden). Any place that’s a blind spot. I don’t recommend the glove box or under the dash. Too obvious. Remember, the car jacker has probably already disabled your alarm, ignition kill, and starter kill system. He’ll deduce that you have a poorly maintained car, or you have another kill switch somewhere.

Remove all panels covering the fuel pump. You will find a round dohicky with a bundle of wires going to it. Yes dohicky is a professional term. Carefully open up the cover of the wire bundle leading to the top of the fuel pump. The bundle of wires split at some point with 3 wires going to the fuel sending unit and low fuel connector, and two wires going to the C566 connector and pump. Mine had electricians tape around it. Locate the yellow/green wire (that’s yellow wire with green stripe). This is the power wire (from ignition circuit) that fires up the fuel pump. [If still confused on the what is what, wires to ignore are yellow/white, black/yellow, black/white, & green/red. They are for sending unit to fuel gauge and low fuel light.] I used the yellow/green wire myself. Cut the wire. Strip some of the insulation off of both ends (just enough to connect with male and female connectors). Locate where you want to install the switch. Figure out how you’re going to affix or attach the switch. If access to connecting the wires is limited, wait until the last minute to glue, screw, or bolt the switch down. I super glued mine. Improvise.

Connect a new section of wire to the wire coming out of the fuel pump. You do have the option to hard wire the circuit. However, I soldered a female connector to the wire coming out of the pump and a male connector on the new wire (more about this later). Use a hair dryer to shrink insulation over the connection. Your option is to use electrician tape. Route that wire to your switch. Solder or use a female plug connector to attach to one pole of the switch. Now, take another piece of wire and connect to the other pole of the switch (female connector or solder). Route that wire back to the fuel pump area.

Connect that wire coming from the switch to the remaining or only loose end fuel pump wire (the one that goes to the circuit and finally to the power). Use a female connector on the wire from the switch and a male connector on the remaining wire. Shrink tube insulate that puppy. The circuit is now complete. The reason I have a male connector on the wire coming from the power circuit and a female connector on the wire from the fuel pump is to have an emergency way to hook up the circuit if the switch fails. Just a failsafe backup. To keep all the wires from chafing or disconnecting, I used small zip ties to bundle the wires to other wires or spots.

Test the switch. Start the car. If it starts, the switch is in the “on” position. Then, switch the switch to the opposite setting. The car should stall out. Taaaadaaaa, fuel pump is switched off. If the car doesn’t start in either setting, you have bad connection someplace. Recheck the circuit. You only have four places that it could be screwed up. The only other problem could be the cheap switch you bought at Target.

If the switch works, finish the install of the switch. Hide it good. Reassemble all the panels. You’re in business. The only thing you have to be aware of is that it is a given you will forget about the switch. You’ll jump in the car, turn the keys, and it won’t start. That’s when you slap yourself silly because you forgot (for the 10th time) that you didn’t turn on the fuel pump switch.  Stupid, stupid, stupid. However, that’s the idea. You want the car jacker to think that you’re a rotten car owner that poorly maintains his car. Won’t start. A more experienced car thief will look for a mechanical fuel cutoff switch under the hood or some other device under the dash or glove box. If the switch is hidden and he doesn’t want to spend a lot of time looking, the thief will split to find an easier target. This security mod is a cheap, extra layer of protection. No guarantees.