Fuel cut switch
 

Hey guys, there's an idea I had of a way to rig my fuel pump to a cut switch for when I am away from my car, but I've gotten several different views from other people on it. Your opinions would be appreciated!

I don't have the A/C in my car, so i have a useless button on the dash. Several cars have been stolen from my area before, and I'd like to prevent mine from being one of them. I figure I can reroute a wire from the fuel pump, up to the A/C button, and back to the fuel pump. That way when I leave my car, I can just turn the A/C "off", and start my car up. It's just an idea, but it's something I'd like to go through with. Comments?

Seems like a good idea and stealthy too. I know my brothers first gen has a fuel cut switch for deflooding it mainly but is also good for security reasons. His isn't any special button but just a switch that he bought and hid away from sight.

I'd say it's the next best thing to having a battery kill switch while still retaining the alarm function...

well, you would need to know what the a/c switch on the dash is rated at, and see if it can handle the power the fuel pump requires. If it doesnt, you could always use an isolation relay that can handle more. Which now that Im thinkin about it, it would probably be a better move to use an isolation relay no matter what.

good luck

Aside from welding the car to a fixed object if they want your car they will get it. It would be a deterent but not fail safe.

yea but then there is that one time you jump in while your in a rush and forget to turn it on... the car will run and then possibly when there is no more fuel then possibly pop goes the motor when it goes lean

The car won't start when the fuel pump is deactivated. And even if it was accidentally hit while running, it would stall before it popped. And a deterrent is much better than nothing IMO. I'm just looking for an "extra step" someone would have to go through before taking my car. If they want to steal it, they're going to, I'm just going to make it THAT much harder for them to steal. Thanks for the opinions, I think I'm going to go ahead and do it. ~A-Rod

y not just get a kill switch?

Because a kill switch would eliminate the alarm function.

Yep :)

I've been researching this for a while but whenever I try and find a switch, its always a 3 prong type switch. Is it possible to wire a 3 prong type switch and use it as a fuel cut switch? If so, does anybody know how its done? thanks

It would be much easier to interrupt the signal wire that the ECU uses to activate the fuel pump relay... the signal wire uses much less current (probably 0.1-0.8A) so you don't need to use a heavy-duty switch.


Most 3-prong switches will connect the center terminal to one of the outer terminals or the other depending on the position the switch is in. Since you only need on or off rather than (1-2) or (2-3), simply use the center pin and one of the outer pins. You'll want a toggle switch rather than a momentary switch: momentary switches are spring-loaded and will return back to their default position... not useful for a kill switch.

Ok so I finally got it to work, thanks for that advice. Another thing, you said that signal wire to the ECU only uses 0.1-0.8 amps. What I would like to do is wire my switch to a connector, so removing the switch will be easy if I ever need to remove it to get to something else and I don't have to cut any wires to take it out.

I'm wondering, would wiring up a (example: coolant level sensor connector) to the ECU signal wire circuit be safe and reliable, or would I need a more heavy duty connector?