adding a fuel preheater

This is for an '02 Rav4. The heater has one ground and one power coming from it. I know how to hard wire it to the battery with a switch, but I don't want to risk forgetting to switch it off and draining the battery. How do I wire it so that it turns on when the ignition is switched to accessories and turns off when ignition switched to off? Thanx

Ummm..... cooler fuel makes more power....... The only time a fuel preheater is a good idea is when running SVO on a diesel conversion.....thins it out and makes it easier on the injection system. Or is this for a Webasto style coolant heater that burns the vehicle fuel? Not a good idea on gas motors, but they do work nicely on diesels.Wherever I go, that is where I end up......

The purpose of the preheater is to aid in the vaporization of the fuel and having it mix better with the air. The result...same amt of power with lesser amt of fuel. At least that's what's been said...and it seems to make sense. Besides, with gas prices the way they are nowadays I'm willing to try it out. I'm thinking of tapping into power from an existing fuse, but that might not be the 'correct' way.

Yes, it will atomize better, but, on a fuel injected vehicle, the ECU will also compensate for fuel temp, and change the injection cycle accordingly. It will still inject the fuel the same no matter what temp it is. As to it atomizing more effectively? I dunno..... I would doubt it. The ECU knows that it takes x amount of fuel per volume of air for combustion, the actual injector nozzles control the vaporization into the combustion chamber. I rate this right up there with the airflow things that have been popping up. No matter what you do upstream of the intake manifold, it is still the same amount of air going into the cylnders, flowing through the intake runners the same way it always does. You want better fuel mileage, get either a more efficient vehicle or have the ECU reprogrammed for a better efficiency curve. A proper regular maintenence schedule is the best way to maintain efficiency. I'd also be wary of heating gasoline.... it is volatile enough at normal storage temps..... heating may very well cause some unexpected results with vapour.Wherever I go, that is where I end up......

Thanx for the diagram. As far as what the heater will do...I'll find out. If in fact it doesn't work, at least i can revert back to the old way. But if it does work, then people have an option to do it for themselves and know that somebody's tried it already with real world results. I've already taken baseline readings and will be recording the mpg results over the next few weeks. I'll keep you guys posted.