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FAQ: DIY: How-to: Fuel Pump Cut Off Switch

Old 07-03-2005, 05:34 AM
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Default FAQ: DIY: How-to: Fuel Pump Cut Off Switch

I'm posting the thread because of someone asking about it in one of my other posts. I searched first and saw that the last guy to post this thread removed all the info (don't ask me why). Hopefully I don't end up doing the same. Anyway, all this info is from crxresource.com. I go there all the time and they have lots of info and some good *** how-tos. The instructions are ridiculously simple to follow too. Later.

Originally Posted by pyro_freak8
anyone have a good tutorial for a fuel cutoff switch?

CRX HOW-TO: SIMPLE FUEL PUMP KILL-SWITCH (without soldering)
A. INTRODUCTION
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!


B. SUPPLIES
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.




C. BENCH WORK
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.


D. IN 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!


E. TEST THE SWITCH OUT BEFORE YOU PUT EVERYTHING BACK!
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.


F. WHAT ABOUT A RELAY?
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.
Old 07-03-2005, 06:56 AM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (knwldge54)

Great writeup
Old 07-03-2005, 07:40 AM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (SwissChEz82)

Updates:

--I didnt want this on my personal website anymore, with the clever theives and what-not.

--I used pliers when I made the writeup (though I have crimpers, I wanted to show it can be done without buying them). Do your connections right with a crimper if you can.

--A relay is required if you do not get a quality switch of at least 20Amps. Dont scrimp on the switch unless you feel like digging into the project in a parking lot while your girlfriend waits.

--The switch in the wrtieup still works without any problems every day.


Old 07-03-2005, 08:13 AM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (SwissChEz82)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SwissChEz82 &raquo;</TD></TR><TR><TD CLASS="quote">Great writeup </TD></TR></TABLE>
Old 07-03-2005, 08:27 AM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (fireant)

i would suggest solder/heatshrink connections rather than butt-splice connectors; i have seen many problems arise from the use of cheap crimp connectors. i have been standing on the side of the road because of those type connectors

i solder all connections unless the sitation won't allow for it
Old 07-03-2005, 08:54 AM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (sam385)

great writeup!

i am planning on doing this to my Civic, and you make it look so easy!

however, you mention that i have to remove the rear seat to access the fuel pump. ive tried to remove the rear seat before in my civic, but i had no luck
does anyone know how to remove it?
thanks!
Old 07-03-2005, 09:06 AM
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Good writeup, but I would solder all the wire not crimp them. But still good writeup

sam385 I also solder all my stuff.
Old 07-03-2005, 09:45 AM
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It isn't my write up. I go around to alot of CRX sites and thought it be alright to share this one.
Old 07-03-2005, 11:51 AM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (knwldge54)

one of the best helpful advices.
Old 07-03-2005, 02:55 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (DaMmniTz)

so now that "everyone" has a picture of where the wire is, and which wire to check

real smart

you think theives dont have computers and cruise the boards? People like me depend on mods like this, and its no use anymore when people are giving instructions to theives on what to check for if attempting to steal my ****.





Modified by crx_91si at 7:05 PM 7/3/2005
Old 07-03-2005, 02:59 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (DaMmniTz)

Great detail on the write-up!
Old 07-03-2005, 03:38 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (crx_91si)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fireant &raquo;</TD></TR><TR><TD CLASS="quote">Updates:

--I didnt want this on my personal website anymore, with the clever theives and what-not.
</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx_91si &raquo;</TD></TR><TR><TD CLASS="quote">so now that "everyone" has a picture of where the wire is, and which wire to check

real smart

you think theives dont have computers and cruise the boards? People like me depend on mods like this, and its no use anymore when people are giving instructions to theives on what to check for if attempting to steal my ****.


[/i]</TD></TR></TABLE>

Honestly, if you install this mod on your car, why wouldn't you install an alarm? I'm not saying an alarm will save your car from being stolen no questions asked but it is a simple way to protect your car when you can't. Chances are that if your CRX has an alarm, you probably won't bother doing this.

Honestly if you feel that's letting everyone know what to look for, get an alarm. Theives never get around those. LOL
Old 07-03-2005, 04:37 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (knwldge54)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by knwldge54 &raquo;</TD></TR><TR><TD CLASS="quote">

Honestly if you feel that's letting everyone know what to look for, get an alarm. Theives never get around those. LOL</TD></TR></TABLE>

Back in 2001, my car was targeted by theives in Seaside Heights, NJ and the $300 alarm i had profesionaly installed was bypased. they got into the car, popped out the lock cylinder for the ign., & tried starting it with a screw driver. It started for 5 seconds (long enough to move it 2 feet out of the parking space), then died.

If i didn't use my switch, i would have been another H-T member posting up another "my crx got stolen" post.

Thats why i posted up what i did.....you just basicly fucked anyone who had a kill switch wired like that. Now when the CRX thats being stolen doesnt start, they'll just rip the cargo box up and look there!


BTW...any idiot can get around an alarm. It's not rocket science
Old 07-04-2005, 03:14 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (crx_91si)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx_91si &raquo;</TD></TR><TR><TD CLASS="quote">
....you just basicly fucked anyone who had a kill switch wired like that. Now when the CRX thats being stolen doesnt start, they'll just rip the cargo box up and look there!
</TD></TR></TABLE>

Everyone isn't putting they're switch in the same place. I don't know how often theives work out but have youe ever tried ripping you cargo box up? I can think of very few people who even if they thought of it would be able to rip out a locked cargo box.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx_91si &raquo;</TD></TR><TR><TD CLASS="quote">
BTW...any idiot can get around an alarm. It's not rocket science</TD></TR></TABLE>

No ****, but is it better to have a fuel pump cut-off or not?
Old 07-04-2005, 06:07 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (crx_91si)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx_91si &raquo;</TD></TR><TR><TD CLASS="quote">so now that "everyone" has a picture of where the wire is, and which wire to check

real smart

</TD></TR></TABLE>

It's called layers - with more layers, it takes more to steal/start a car. Those few seconds/minutes may save your car.

Besides, the amateur thieves probably wouldn't even know what to do with this information and the pros already know it.
Old 07-04-2005, 07:29 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (senpai)

I was thinking about another 'fuel-cut' method - disable the injectors? Lots of EF's use resistor boxes, and it'd be simple to put a switch or relay to break that connection. Theives would also have to hunt through the engine's wire harness to find out how you disabled the car.

Anyone know how much power goes though the resistor box, or at least through each injector? I'm guessing maybe 10 amps per injector (IIRC, DIY resistors are ~10ohm & 10amp). My other idea would be to disable 2-3 of the injectors, make the theif think the car is just a broken POS.


Lastly, the main idea behind a anti-theft device is to make the theif stay there longer. The longer they stay, the higher the chance of being caught, meaning risk outweighing reward.
Old 07-04-2005, 08:08 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (crx_91si)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx_91si &raquo;</TD></TR><TR><TD CLASS="quote">

Back in 2001, my car was targeted by theives in Seaside Heights, NJ and the $300 alarm i had profesionaly installed was bypased. they got into the car, popped out the lock cylinder for the ign., & tried starting it with a screw driver. It started for 5 seconds (long enough to move it 2 feet out of the parking space), then died.

If i didn't use my switch, i would have been another H-T member posting up another "my crx got stolen" post.

Thats why i posted up what i did.....you just basicly fucked anyone who had a kill switch wired like that. Now when the CRX thats being stolen doesnt start, they'll just rip the cargo box up and look there!


BTW...any idiot can get around an alarm. It's not rocket science
</TD></TR></TABLE>

You can put ur kill switch anywhere. It is about layers of security. And who only has one alarm in their ride? I have the main one plus 2 stand alones and several other goodies I won't share here. Trust me when you have 2 stand alone mini peizo sirens blaring, finding a skill switch aint gonna be worth it.
Old 07-05-2005, 08:23 AM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (korean_teg)

His posting this isn't going to alert the whole thief community to it and make it useless. In fact, kill switches were commonly known to car thieves way back before any of us got our license to drive. It's worth the risk of teaching some HT junior thieves if everyone starts doing this. Even if thieves are tipped off, it will still cost them some time compared to if there was never a kill switch in the first place because the owner was never given the idea.

I suggest tapping into the wire further upstream, and not right on the fuel pump. If everyone has a different location for tapping into the wire, thieves can't wise up to it. It doesn't matter where you put your switch if they can find where you tapped into the wire. You can go as far upstream as the fuel pump relay under the dash.

Also, there are a number of other circuits to put this switch on. Take a look at your main relay for instance. Any critical wire will do, but if it's a heavy gauge wire, use a relay.
Old 07-05-2005, 07:48 PM
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haha might be ultra low-class, but i just pulll my ECU fuse and lock the hood(lcking hood pins). but thats only when i go to high risk areas other than home
Old 07-05-2005, 08:04 PM
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Default Re: FAQ: DIY: How-to: Fuel Pump Cut Off Switch (knwldge54)

Nicely done
Old 07-05-2005, 08:04 PM
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i got a quick question. after we cut the wire and put the butt connectors in, we plug the gray harness back together right?
Old 07-05-2005, 08:11 PM
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If you insist on using crimp connectors, get a nice tool for the job:



These tools are great, better than pliers..or so I think. My local store has the tool for 10 bucks, the dies for maybe another $10..twenty dollars well spent IMO
Old 07-05-2005, 08:54 PM
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If you wanted to hide the switch in plain view you could use a button on the dash/console for an option ur vehicle doesn't have such as a/c or something. You could also combine the switches so that they have to be turned on in a group for the pump to be on.
Old 07-05-2005, 09:18 PM
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Default Re: (EGsixx)

Use non insulated butt connectors, heat shrink, and get yourself a heat gun at harbor freight. That **** will be so clean you'll want to show it off. Those butt connectors pictured are okay for some things, but nothing too critical because the insulation cracks when you crimp them. You can then wrap them with electric tape but that's just ugly. Vinyl insulation is good with a heat gun but it tends to tear. Non insulated butt connectors are very cheap and you should try and find a real electronics shop besides radio shack anyway.
Old 07-05-2005, 09:43 PM
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i got a switch i had laying around and it has 3 plugs commin out, it has POWER,ACC,GROUND do i just plug it into power and ground only?

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