fuel cut relay

I would recomend against method 2, as the relay will be energized whenever the car is off and the alarm is armed.  This will put a ~200mA load on you battery at all time, roughly 4x the 'normal' acceptable load on a cars electrical system when not running.

The 'relay 1' method won't work either how you have it, as you can't use pins 87 and 87A like that.  You need to use 87A and 30.

The first method doesn't actually cut fuel until the ignition is turned on (the first thing you do when hotwiring a car.  At that point, the fuel pump will be disabled, making it 'impossible' to steal the car.  The downside to this is that IF they try to hotwire the car they will most likely be able to hear the relay clicking on and off with the ignition, which makes it very easy to bypass it.

You could always go with solid state relays - no clicks and VERY low load.

So a standard "starter kill" is not ideal for a cars electrical system as well? Is it not the same theory? You "open" the starter wire when you arm the car, you open the fuel pump control when you arm the alarm.... it's the same thing.... isn't it?

KarTuneMan,

I've never seen a 'standard' starter kill that uses 12vdc on one side of the relay.

How much current does a standard Bosch relay pull?  I've seen them routinely read >225mA.

How long will the reserve capacity of an OEM battery support a 225mA load?  Lets say there is a 120min reserve at 25A (Optima specs).  Also, remember this load is in addition of anything else that the car is already drawing at rest.  I have fixed cars that would have the battery die if left sit for 4-5 days.  I personally would rather have someone steal the car then worry about jumping it every time I leave it sit!

Most of my alarm installs have been DEI.  The starter kill relay has an orange wire and a yellow wire.  The orange wire is (-) when armed and the yellow wire is ignition (This is what I consider 'normal' for a starter kill application).  I did some Audiovox alarms and I always hooked the starter kill relay up the same way.  If you know a way to prevent the battery from dying if left sit for a few days please share.