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HybridZ

almost lit my car on fire!


260zjade

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THe easiest way to disable the car would be to install a relay inline with the power to the fuel pump. Depending on the year the relay is in differing places, on my 78 it's under the black box under the hood (the one the fuse links bolt to)

On all fuel-injected Z's the FPR has ground all the time when the key is on, and switches on and off by providing a 12v signal.

The 12v signal goes through the ECU, so once you find the wire you can install the relay in line so it can cut the signal to the fuel pump relay. Search the megasquirt forum, I installed an MSII into my Z and the stock pinout is in there.

The field coil terminals then get hooked to ground and to 12v thru a toggle switch that you can hide. (The filler panel that is under the steering column shroud is a great place, the column shroud hides a button nicely)

This would be how you hooked the relay up:

 

Terminals-what to hook to it

30-wire to fuel pump relay

85-12v FPR wire (from ecu)

86-12v from toggle switch (momentary if you wired the relay as "holding")

87-ground

 

Hook the toggle switch (you could use a momentary switch if you wire up the relay to be "holding"..I don't know exactly how to do it but it involves a diode from relay power to the field coil terminal....then it would stay "on" until you shut off the car.) to a switched ignition 12v source, and the other side goes to relay terminal 86

(check first, though, all relays are different, so make sure the contacts and field coil terminals are correct! It will have a diagram on the relay.)

 

Hide the switch in a place that only you know about. (potential thief will think it's for a valet feature for an alarm-this is a very effective deterrent, no fuel, no start....but it will still crank and the crook will think the car is a POS..it will start and run for a few seconds till fuel pressure in the rail drops, and the crook will think it's broken...and will go elsewhere.)

Good luck!

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savageskaterkid wrote:I think they're called magnetic switches.

Umm...that's what a relay is....a magnetic switch. Whether they stay on when field coil power is removed or not depends on how you wire them.

An example of a HUGE relay is the starter solenoid, which is exactly why you don't want to wire the lighter in series with it...the field coil terminals on a starter solenoid still draw a few amps

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