Installing a fuel pump cut-off switch

    One of the easiest security measures someone can have in the vehicle is a fuel pump cut-off switch.  Not a mechanism that is wired into your alarm, because that can still be bypassed.  But, an actual switch inline with your fuel pump wiring.  This is not a guarantee that your car will never get stolen, but if you hide your switch (or possibly switches) well, then it might deter a would-be thief.  And for less than ten bucks and a little bit of your time, how can you go wrong?!  There are quite a few different ways to do this, this guide is only one.  I would also suggest checking out THIS METHOD. I might be revising this guide to do that.

    Keep in mind this is for my 1994 Civic, but the principal is the same for ANY car.  Most Hondas will have the fuel pump power line marked as a Yellow/Green wire, but if you have another car the correct wire is just a service manual away.


*Disclaimer*:  I am not responsible for any damage incurred to vehicle or individual.  This worked flawlessly for me, but that doesn't mean something couldn't happen to you.


Here is what I picked up for the job (all from Radio Shack):    

   -  25A Automotive rocker switch, Part#275-730 (I don't recommend the lighted switches, I had issues with the one I got, plus why would you want a light on a switch you are trying to hide)

      *Note*  I recommend that a 25A switch be that absolute minimum you use for this application. 

   -  18 to 14 gauge wire (the thickness of the wire is dependant on how far away you will be mounting your switch(s) from the original splice of the yel/grn wire.  You can use the thinner wire if the switch is close)

   -  Crimp on butt connectors (Red), Part#64-3037 (these are useful if you don't feel like soldering, and they work just as well)

   -  Heat shrink wrap or electrical tape


Things I didn't install, but should have.:

   -  Heavy duty inline fuse holder - This will go on the power line between the pump and the switch, and is just another safety measure. An example of this is Radio Shack part #270-1217.


Other tools you may need:

   -  10mm open ended wrench

   -  Wire cutters

   -  Needle nose pliers or a wire crimper (for crimping the butt connectors, if you use them)


    Before I started cutting wires on the car I prepared my switch.  I went ahead and soldered on the wire I was going to be using and cut the wire to a length I knew was going to be much more than I needed.  When wiring a non-lighted SPST (single pole single throw) switch, the top blade is typically the POWER side.  Meaning that this is where you solder the wire that will be running the side of the fuel pump wire that provides the power.  The middle blade is the LOAD side of the switch.  Which means this is where you would be wiring the side of the fuel pump wire that goes directly to the pump.  Check out the picture to see what I am talking about.  This picture shows a lighted switch (the one I think is a bad switch), but it's the same principal.  The RED wire is what I will be using for power, the BLACK wire is what I will be using for the fuel pump side.

      Switch_layout.jpg (42113 bytes)


Before doing anything, unhook the battery.  This is common sense.


    Alright lets dive right in.  First we have to remove the bottom cushion of the back seat.  If you have something other than a 92-95 Civic then this procedure may be different.

  1. Lay the tops of seat down like you would if you were loading something in the car.

  2. Pull up the fabric that covers the spare tire.  Pull it up enough so you can see the bottom of the back seats, like in this photo.  I had already removed this nasty fabric entirely, just for the hell of it.
    rear_seat_bolt.JPG (54455 bytes)

  3. Use your 10mm wrench on the single bolt in the back.  It can be somewhat of a pain to get to.

  4. After you have that bolt removed, pull the tops of the seat back up and get inside the car.

  5. Pull the cushion up by the front first.  You will have to lift up and pull back, as there are little hooks holding the front of the cushion in.

  6. After you are done you should see this.
    fuel_exposed.JPG (69655 bytes)


    Now it's time to start cutting.

  1. Pull the little bit of carpet back if you need to, and unwrap the wires.

  2. Find the YELLOW wire with a GREEN stripe
    yel-grn_cut.JPG (67154 bytes)

  3. Cut it where ever you like.


    This next part is assuming you already have your switch mounted where you like it, and the wires run.

  1. Strip about a quarter inch or a little more off the ends of the wires.

  2. If you are using shrink wrap, make sure to put in on now.

  3. Insert the appropriate wires into the butt connectors.  POWER wire goes to the part of the YEL/GRN wire running up front, LOAD wire goes to the YEL/GRN wire going to the pump.

  4. Then they will look like this:
    power-load_crimp.JPG (74267 bytes) power_crimp.JPG (65492 bytes)

  5. Now wrap up the connections neatly.

  6. Put the rear cushion back in place.  You might need to bump the front of it around to get the hole lined up in the back for that 10mm bolt.


    Time to test.  Hook the battery back up.  Flip the switch to the ON position (the "|" position), and start the car up.  If the car starts up that means everything is wired up correctly and nothing has blown.  Now flip the switch to the OFF position (the "0" position), the car SHOULD stall out and you won't be able to start it back up with out flipping the switch back on.


    If the car doesn't start with the switch in the ON position, you may have blown a fuse.  Check the number 2 fuse underneath the dash, it's the one show in this picture:

     pump_fuse.JPG (33998 bytes)

It's normally a 15A fuse, but I temporarily switched mine to a 25A, because I ran out of 15A fuses.  I kept blowing fuses when I tried using that lighted switch shown at the beginning of this article.  So I switched to the other switch (which I was saving for my starter kill, hehe) and everything worked fine.  I might have had a bad switch, anything is possible.


    That's it.  You can see how easy this can be!  Obviously I'm not going to tell you where I put my switch, but I had to do some "Dremel" fabrication to get it to hide well.  You are only limited by your imagination.  ALSO, you don't HAVE to cut the wires where I cut them.  The wiring for the pump runs along the driver's side door sill, so all you would have to do is pull up some carpet to splice a wire in there, JUST REMEMBER IT'S THE YELLOW/GREEN wire!  If you are feeling squirrelly you can install more than one switch too, in different areas obviously.  Keep the bastard thieves guessing.