71coupe

I figured out a way to install an anti car jacking device into my fuel system.
Here's the clincher - you need to have an electric fuel pump & a carb, no F.I.
No buttons to press to activate the system - just open the door.
The car dies when the carb fuel bowls empty, 30-60 seconds.
E-mail me for the plans. I can't post pics right now.
h455@hotmail.com


[Modified by 71coupe, 9:24 AM 11/30/2001]

71coupe

Can anyone post an image for me?
I'll email the schematic to you.

lbell101

Ya - no problem - email it over!
lbell@chartermi.net

lbell101

OK - here's a link to the schematic. Too big to just display here.
Schematic Here

71coupe

Thanks for posting the link Larry :cheers:

Note: Diagram is with power off with and all switches open (off)
& don't use the lighter for a switch, it may not work (see gerry's post below)
Use a momentay switch instead.

How it works:
You get in your car & push in the cig lighter. It energizes relay 3 & 2 _ which turns on the fuel pump. Start the car.
Note: The car may still start if you don't press the lighter, but it will only run long enough for the carb to empty.
After the car starts, cig lighter pops out & kills relay 3. Relay 2 is still on & relay 1 will be on at this point.
Relay 1 will be energized only when switches A, B, & C, are closed & the key must be on. If you kill relay 1, the only way to turn on the pump is to push in the lighter again.
You could also use a momentary micro switch instead of the lighter - it may be easier to install.
You just need to tap it once, no need to hold it to keep the motor running or while you are cranking it over. The idea for the lighter or momentary switch ensures that the system is self-resetting. You just turn off your car to arm it, no need to remember to turn on your kill switch. That green jumper wire keeps relay 2 energized when relay 3 is de-energized.

With the motor running or key on, relay 1 controls the system.


Switch A: Oil press switch. Safety item -switch opens if you lose oil press by lack of oil or motor is turned off. Switch closes when motor has a min of 5 psi oil press.
Switch B: Inertia switch. This is a safety item & the switch is always closed. It will open if the car is hit & can be reset. Cam Potter gave me the idea on this one _Thanks Cam.
:yesnod:
Switch C: Door switch. The driver door must be closed for this switch to close. This is the anti-car jacking switch. If the door is opened with the key on or the motor running, it will de-energize relay 1. you will have about a minute before the motor dies (enough time to get to safety)
The only way to reset the system is to push in the cigarette lighter (before the motor dies)

You can build this cheaply. I bought 3 30 amp relays from Radio Shack for 20 bucks. I got the oil press switch from Jegs, & the inertia switch from a wrecked 91 Mustang.
The door switch is from Crutchfield. It's made for door speakers. Just jump the connections in the door.

(I forgot to label the battery - lwr r/h corner. Also, the blue wires are the relay "pull-in" circuit, the red wires are the main load wires-heavy gauge, & the orange wire is for emergencies in case one of the relays fail - it will get you home)

Do I have too much time on my hands or what?




[Modified by 71coupe, 2:19 PM 11/30/2001]

lbell101

No problem!
I thought it would overwelm the board to post direct but it works!
Interesting idea. If I lived in a more crime ridden area I'd probably do it.

ZD75blue

wow... i think it will work... i may have to try this

ZD :cheers:

gerry c

I don't think it will work. It looks like the ground for the lighter goes through the relay coil (suppling power to the coil). This is fine to operate the coil, but it will not flow enough current to have the lighter get hot enough to pop out. Typical relay coil MAY have 100 ohm resistance. The most current you could pass through that would be lees than a 1/10 of an amp. A 1/10 of an amp (really less) will not do squat to heat a lighter to make it pop out, let alone use.

Using a momentary switch would work though.

71coupe

I thought that the lighter may be an issue. I think you could use the cigarette lighter if you added an additional terminal next to the lighter power terminal on the bottom of the lighter socket using a rivet.
That way, it doesn't go through the lighter - it just uses it for the connection when it's pushed in.
The micro momentary switch would be easier to do though.
I'll have to look in the lighter socket to see if it would work.





[Modified by 71coupe, 2:00 PM 11/30/2001]

mrvette

I had something similar to that in my GTO once.....simple relay latching arrangement....

the interior lights HAD TO BE ON, one way or another...the key in the ignition and turned to RUN position....THEN hit the switch well hidden under the driver's seat....at one point it was TWO switches in the correct order...

GENE

rainman69

I've been playing with this, and the only problem I see right now is that will only provide about 10.8V to the fuel pump when all is said and done. Still tinkering...

Anybody have an estimate on what kind of current an electric pump pulls? :smash:

rainman69

Well, my tinkering...and one suggestion. Add the 4th relay to keep current draw from the ignition switch down in the mA range. Using standard EE drawing convention, wires that are not connected where they cross do not have dots.



:smash:

gerry c

What's with akk the 12ks to grnd after the relays? All I see them doing is draining power for no reason.

Also, why did you earlier say the fuel pump would only get 10.8 volts? The relay contacts should have no voltage drop. They are not solid state switchs, there would be almost no voltage drop across them.