d16rice

Does a fuel pump ever supposed to shot off between the time the engine is started and the time the engine is shut off?

Also, what is the minimum and maximum voltage required to run the fuel pump.

Luserkid

If the car is ON then the pump is on. If the car is off the pump will be off and depending on how low the fuel pressure is the pump wont need to prime.

Sorry dont know the voltage.

Honda V-Tec

Runs around 11.9 v

d16rice

Thanks, I read that fuel injectors sometimes shut off to conserve gas, but I heard nothing about the fuel pump.

The reason I'm asking is because I came up with this relay combination that would prevent a car from being stolen.

V
V
V

Below is a diagram using five relays for a fuel cut-off.
I know it seems like an overkill for a fuel pump cut-off switch, but if you look at the diagram and understand what it does, you’ll know that it’s one of the best kill-switches you an possible make.
Before starting the car, you’d have to push the AUX/Trunk button on the remote to make a closed loop circuit for the fuel pump to run. No remote=no fuel pump.
With this, the cut-off switch can be wired in right next to the fuel pump, under the seat, making it almost impossible to disable without getting noticed.

Once the engine is turned off, the switch disconnects itself, making it impossible to restart without pushing the AUX/Trunk-release on the remote once again.
Best of all, the activation switch will always be safe in your pocket.



For those who care, this is how it works.
When you push the AUX/Trunk-release button, you activate the “orange” relay.
The “orange” relay completes the closed loop circuit, allowing the 12 volts to travel through and activate the “purple” and the “green” relays.
The “green” relay is a double throw relay, meaning it activates two thins simultaneously. One thing is does is it allows the 12 volts to be constantly running through the circuit (to self sustain itself). Another thing it does is it completes the closed loop circuit for the fuel pump.
At the same time the activated “purple” relay disengages the AUX/Remote to avoid any interference.
Now the fuel pump circuit is armed and ready to go.
When you start the engine, the “blue” and “yellow” relays are activated. The “yellow” relay allows this part of the circuit to self-sustain, while the blue one disconnects the power supply to the previous loop.
When the engine is shut off, the “yellow” relays brakes the loop and makes it impossible to restart the car without activating the “orange relay” (pushing the button on the remote again).

I haven’t done this yet myself, so at the moment it’s only theoretical, but I will do this to my car within the next two weeks.

jlacoy82

What happens if you lose your remote or the batteries die?

Looks like a good idea though, no physical switch to be bybassed, unless they managed to rewire the original wires to the fuel pump.

d16rice

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlacoy82 &raquo;</TD></TR><TR><TD CLASS="quote">What happens if you lose your remote or the batteries die?

Looks like a good idea though, no physical switch to be bybassed, unless they managed to rewire the original wires to the fuel pump.</TD></TR></TABLE>

This is made to be wired into your alarms auxiliary/trunk-release output.
Alarms usually come with two remotes, and have additional ones for sale in case you loose your original one.

Also, if you battery dies, the fuel pump won't run either way, weather this is installed or not.

Best of all, if the thieves decide to rip out the brain unit, they'll disable the fuel pump at the same time, making it impossible to start.