Switch that interrupts the ground circuit

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plumkrazee70

plumkrazee70

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I want to put in a anti theft device on the ground circuit of my fuel pump. Can I just get a two prong switch, and wire it in series of the ground circuit?

My thinking is when it is off, the circuit won't be completed, therefore no power to pump, flip it on and circuit completed.

Am I thinking about this correctly?
 
as long as your fuel pump is not internally grounded should work. watch the amperage, and switch and wire accordingly
 
Assuming the fuel pump is powered by a relay... interrupt the relay coil signal. Smaller gauge wire and lesser grade switch req'd.
 
Good idea. Most Starter And ignition cutouts are pretty easy to bypass.
 
plumkrazee70 said:
I want to put in a anti theft device on the ground circuit of my fuel pump. Can I just get a two prong switch, and wire it in series of the ground circuit?

My thinking is when it is off, the circuit won't be completed, therefore no power to pump, flip it on and circuit completed.

Am I thinking about this correctly?
Click to expand...
Yes.
 
RedFish said:
Assuming the fuel pump is powered by a relay... interrupt the relay coil signal. Smaller gauge wire and lesser grade switch req'd.
Click to expand...

THIS RIGHT HERE.

There are several ways to "sneaky" anti-theft some in plain sight

Guys used to advocate wiring the cig. lighter to the tach wire. Push in the lighter--if it's clean--grounds the coil NEG. Does not work very well on MSD LOL

If you have any other relays in the car, for ignition circuit, etc, same deal, interrupt the coil circuit.

You can ALSO buy electric fuel cutoff solenoids (for mechanical pumps)
 
Just make sure the pump isn't running when you remove the ground connection. General practice is switch hot wire not ground. You can get large arcs when a ground goes away under power.
 
plumkrazee70 said:
I want to put in a anti theft device on the ground circuit of my fuel pump. Can I just get a two prong switch, and wire it in series of the ground circuit?

My thinking is when it is off, the circuit won't be completed, therefore no power to pump, flip it on and circuit completed.

Am I thinking about this correctly?
Click to expand...

Krazee

That will "work".

HOWEVER, here is why I wouldn't do it this way. In this plan, you will be running quite a few amps through the switch, and the quality of your switch will determine how good of a ground you will have for your fuel pump. If you are using a really-good high amp switch for this, then you will probably be fine in the long run. If you are using, say, a cheap lit rocker switch from the racks of your local O'really's, then in a measure of months or years, you may be chasing after intermittant or inoperative fuel pump issues! Possible symptoms--the switch is hot to the touch, the plastic in the back melted, etc.

I don't know what pump your running or how many amps it draws, but I am entirely with RedFish on the best way to do this. Interrupt the low-current side of a fuel pump relay (the coil).

Are you using a fuel pump relay?

David
 
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