Kill switch question

[dipso]

I did this Pelican Technical Article: An Easy and Inexpensive Ignition Cut-Off Switch
several years ago. I had points at the time and it worked great.

Now I have changed my ignition system to a magnetic pick up distributor with a MSD6al.
The last few days my tach has not been working and just today as I was driving I realized I had the kill switch turned on.
I thought 'that's weird. the car shouldn't be starting with the kill switch turned on". I flicked the switch and the tach started working.
I was happy about that.

Problem is. Now I have a switch in my dash that only grounds the tach, no longer grounds the points.
Can you guys think of another wire that I could split and send to the switch that would work as a kill switch?

I realize I could ground my fuel pump wire and that would stop the fuel delivery, but that only kills the car after it has been driven a few miles.
I really liked the kill switch to the points.

What else up in the trunk would be a good choice to use?

[James Brown]

You can kill (open) the big red power wire coming from the starter. Or wherever you hooked it up to. But, if yours is like mine, killing the ignition with the key on will keep the fuel pump running (no airflow sensor). So ideally you need an ignition kill and a fuel pump kill set-up or do the battery disconnect with an alt. saver circuit.

[spuggy]

Originally Posted by dipso

I realize I could ground my fuel pump wire and that would stop the fuel delivery, but that only kills the car after it has been driven a few miles.

Have you tried it? Based on my motorcycles, I'd expect that even with float bowls, you'd be unlikely to get to the end of the street. With CIS, I'm betting nowhere near that far.

Earlier 911s with CIS fuel injection ('73-75) have no fuel pump relay. They are directly wired from the ignition switch to the fuel pump. This third version kill-switch can be used on these cars as well as most other later cars were you will want to shut off the fuel pump (914, 944, 928, etc.).

For this version we will use a factory Porsche relay kit. This consists of a relay plug (part #901.612.333.00 - $28.49) and a round black relay (part # 911.615.109.01 - $19.20). When installed, this will have a factory appearance as seen in pre-1989 911s fuse boxes.

When this relay is installed power will flow through the relay from pin #87a to pin #30. If the fuel pump is connected to pin #30 and power to the pump is connected at pin #87a, every thing will operate normally (see diagram #3). However, if pin #86 and #87a are connected together and pin #85 is grounded, the fuel pump (or whatever is connected at Pin #30) will not operate. Pin #87 should not be connected to anything (see diagram #4).

A grounding switch can be installed to the interior of the car to activate the relay when desired. The biggest advantage to this type of switching is that a bad relay can never keep you from starting your car as the relay off position starts the car.

From http://www.dietersmotorsports.com/tech/2000/2-00.html

[James Brown]

Dipso has PMO's

[spuggy]

Originally Posted by James Brown

Dipso has PMO's

I still doubt he'd get 100 yards. None of my motorcycles would - and the worst of them did 50 MPG.

Fuel level doesn't have to drop very far in a float bowl - e.g. below the level of the jets where they pick up - before the carb doesn't work. Bowl doesn't need to empty completely.

[James Brown]

True, when I shut off my fuel pump, killed in about 7 seconds at idle, good enough for me.

[dipso]

That sounds like a good idea. Nice and easy too, my fuel pump is in the smugglers box.
I'll experiment.

[JP911]

Originally Posted by dipso

Problem is. Now I have a switch in my dash that only grounds the tach, no longer grounds the points.
Can you guys think of another wire that I could split and send to the switch that would work as a kill switch?

I realize I could ground my fuel pump wire and that would stop the fuel delivery, but that only kills the car after it has been driven a few miles.
I really liked the kill switch to the points.

What else up in the trunk would be a good choice to use?

Put the switch in line with the skinny red wire that supplies switched power to the MSD. I wouldn't break the heavy wire from the starter, too much current.

[dipso]

Originally Posted by JP911

Put the switch in line with the skinny red wire that supplies switched power to the MSD. I wouldn't break the heavy wire from the starter, too much current.

Oh yeah, I agree. I would never touch the big wire.

My concern was about taking a power source and grounding it. Wouldn't that drain the battery over time?

I like the fuel pump idea.

[James Brown]

Yeah, sorry, use the small red wire, more better. And don't ground that wire, just open it.

[dipso]

Originally Posted by James Brown

Yeah, sorry, use the small red wire, more better. And don't ground that wire, just open it.

Your trying to kill me.

[dipso]

All right guys, here's what I did.

I had to figure out how to use my existing switch and wires. The old wire that I split was the purple and black tach wire up in the trunk. I disconnected the wires to the switch and put those wires back together. Now the tach works fine and the switch is no longer connected to the tach.

I looked around in the engine compartment and tried to find a wire that I could use. I remembered the MSD comes with a theft deterrent wire. I read the instructions ( I keep everything) and it says that if you use the magnetic pick up, I think thats purple and green, you don't use the white wire. But the white wire can work as a theft deterrent if it is connected to a switch then to ground.

My existing purple and black in the engine bay is connected to the orange wire that goes to the MSD tach signal. I tried touching the white wire to that and it killed everything. I touched the white wire only to the purple and black wire and thought that would be easy but it didn't do anything. I touched it to the orange wire and the car died.
I guess you cant do that.

What I did was find an unused wire, I have plenty of them back there from the old heater blower and CIS and defogger. There was an old connector that had a green and red wire and a brown wire.
I found the green and red in the fuse block and read the cover. Bingo! it was for the old heater blower and still ran up to the trunk.

I plugged the MSD white wire into the green and red heater blower connector and then fished the green and red wire out of the fuse block. I touched that to the wires from my kill switch and one of them killed the engine.
I clamped those together and now the switch when up, runs the car. When down grounds out the MSD.

Back to normal, I like it.

[911pcars]

Originally Posted by James Brown

True, when I shut off my fuel pump, killed in about 7 seconds at idle, good enough for me.

My car seems to get better fuel mileage with the FP off. I can drive about 2-3 blocks before it sputters to a stop. Must be special technique.

If you're confronted by a car jacker, it's better to allow him (or her) a brief ride down the street than for him to attempt to start a dead engine.... with you still in the vicinity.

Sherwood

[teenerted1]

when i thought it was the MSD that was bad i was in a panic...then it turned out the small red switch wire was the culpret. if i do put in a kill switch it will be one of my options. but i think the switch at the battery ground is a more useful option