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    DIY fuel cut off switch

    david hutcho

    Posts : 18
    Join date : 2011-02-17
    Age : 24
    Location : derby

    DIY fuel cut off switch

    Post  david hutcho on Sat Feb 19, 2011 10:04 pm

    i copyed this from a guy off honda-tech so i dont know if this write up is correct. but here is a write up for a ef/CRX fuel cut of switch. i dont think itll differ much from cars to be honest its probably just a wire colour change. well hope this helps.

    CRX HOW-TO: SIMPLE FUEL PUMP KILL-SWITCH (without soldering)
    Author: sts2soon

    The DC and EG community seem to have their act together with fuel pump kill switches, but nobody has made a how-to for making one for the CRX or EF. The setup is virtually the same, but the wire colors are different. I'll attempt to show you how to make one yourself, but I'll leave it up to you to decide where to conceal your kill switch.

    These instructions are specifically for a CRX. If you have a EF civic (1998-1991) the wires should be the same, but the fuel pump is accessed under your back seat instead of the CRX's "security box."

    I'll start by claiming no responsibility for you messing up your vehicle. This is not a hard project, but the consequences of messing up can be significant. Though this requires no soldering, if you have never worked with wiring then do not start here!

    Here are the parts you'll need to pick up first. I was able to find my wiring, switch, and connectors at the nearby auto parts place:

    A hide-able switch that can carry 20 Amps or more. The Amp capacity will be on the packaging. It should be a two-post switch that has a definite "on" or "off" position, not a momentary switch that is only on while it is being held down! I dont recommend using a lighted switch for this project:

    Spade connectors (These handle 22 to 18 gauge wire, and the blades will fit the posts on my switch):

    I like to use spade connectors because you can take things apart later without cutting the wires, and they provide a good firm connection. This will be more convenient if the switch fails someday.

    Butt Connectors for splicing wire ends together (these can handle from 22 to 16 gauge wire):

    These provide a good connection without soldering...much better than tape alone.

    Some electrical tape, wire cutters, good pliers (for crimping), a hobby knife, and a regular phillips screwdriver. An electrician's tool is nice for stripping wires quickly! Also, get enough 18 gauge wire to reach from the switch to the fuel pump twice, plus more so you wont have trouble accessing the concealed location later.

    I call this bench work because you'll do a much better job if you do it at your desk or table, and not hunched over in the back of your car. It's important to be neat and thorough, so take your time. Dont get impatient!

    Measure out your wire and cut off two lengths that will reach from the switch to the middle of your security box (or back seat on EF civics).

    Strip about 1/4" from both ends of both wires, and put blade connectors on one end of each wire. Test the blade connectors by tugging the wires to be sure they are firmly in place. You should now be able to connect the wires to the switch like this:

    As long as its a two-post switch you can use either connector for either wire.

    Now wrap electrical tape around those connectors!

    Next, go ahead and crimp butt connectors onto the ends of those wires. You are now prepared to put the switch into the car.

    Once you figure out how to squeeze into the back of your CRX, here are the 6 phillips screws you need to remove to get the security box out of the way.

    Remove the box and you'll see this. The wires coming out of the aluminum dome in the middle are what power your fuel pump and fuel level gauge.

    Unplug the small gray harness, then very carefully use your hobby knife to cut away the black wire wrapping from the bundle of wires that go into the silver dome. You will then see 4 wires.

    Put the switch onto the Yellow wire with a small Black Stripe; it provides power from the relay into the pump.

    Why not use the Black ground wire instead? It has been confirmed that it does work on the Black wire. I decided that if the switch were to fail on the Black wire, the next thing "upstream" from it would be the pump itself...which I would hate to replace if it were electrically damaged.

    To attach the switch in-line on the Yellow/Black wire, you first cut the wire about 1" in from the harness (so you have enough to work with) then strip both ends by about 1/4". You can now attach the butt connectors on your switch wires to the those ends. It does not matter which end you connect to which. Tug-test the connections for firmness.

    You're almost done, but don't put it all back together yet!

    What if it doesn't work?
    If your car doesn't start with the switch in either position, you might have a bad switch or the wrong kind of switch. Remove your keys, unplug the little gray harness, disconnect the switch, put the two blades together and tape them up firmly, then reconnect and test again. If it works, the problem is in the switch.

    Still no go?
    Look under the steering wheel at the fuses there for fuse #14. It's a 10 Amp fuse labelled "Alternator Solenoid". It might be blown.

    Still wont start?
    You've possibly damaged your main relay or fuel pump. :'( Plug the small gray harness back together and snap it back into place.

    Put your keys in the ignition and turn them to the "on" position (not start!), while you listen carefully for the hum of the fuel pump. If it makes the priming noise, then your switch must be "on" and you can start your car. If it doesn't make the hum, then your switch is "off" and you wont be able to start. Go ahead and try it out.

    If it works, wrap everything in electrical tape. Spare no expense on electrical tape!

    Then you can put it all back together and sleep better at night knowing the creep who tries to take your beloved car will have a hard time doing it without a tow truck.

    I recommend keeping a knife, phillips screwdriver, electrical tape and a spare 10Amp fuse in your car from here on, so you can splice it back together if the switch ever fails you.

    This how-to is the simplest way to do it. You can also use a relay, which is like a switched-switch. A relay has 4 leads. By using a relay, a tiny, low-amperage switch can be used activate the fuel pump power lines safely. The relay acts as the messenger between the tiny switch and the fuel pump power feed. If this setup ever fails me, I'm going to make one with a relay.
    Read more at http://www.honda-tech.com/showthread.php?t=1297327&ktrack=kcplink

      Current date/time is Wed Dec 12, 2018 11:44 am