Pink resistor wire question

[Horsman]

On my 67 Mustang GT equipped with a tachometer, was wondering what someone was trying to do here, see pic ? I have been trying to isolate a problem why my car will stop running for no apparent reason. I was following the pink resistance wire from the connection at the back of the tach over to the driver kick panel area, noticed what appears to be the pink wire cut and someone stripped back the wiring then added the orange wire with female connector plugged into the resistance wire from the tachometer. I am running a Pertronix with 12 V going to the distributor with a jumper harness in between the ignition switch and tachometer input. I appreciate the help.

[68blk500c]

maybe (?) something is this recent topic will help you:

http://www.saacforum.com/index.php?topic=11430.0

[shelbydoug]

One of the risks in running the power to the coil through the tach is that if the tach fails, the car won't run.

You may be describing that scenario. I would suspect the tach itself.

You have the Petronix wired correctly as far as I can tell.

You can bypass the tach by just unplugging the input wire into the tach, disconnecting the output from the tach and plug the ignition wire directly into the pink wire. If the car runs fine that way then it's the tach causing the issue.

[Horsman]

Thanks for the help. This is my first Ford so I am learning a lot. Prior to my ownership of the car it had been sitting for over 40 years in storage but only has 20,000 original miles.  Car was drag raced most of its life. Since going through the drivetrain, I got the car running and I've put approximately 100 miles on it trouble free with a working tach. Since the car left me stranded, I started looking around, followed the pink resistance wire over to the kick panel area and saw a big blob of electrical tape. I unwrapped the tape, found where the red wires insulation had been stripped back and someone soldered that orange wire with the female bullet connector. It was plugged in to the pink resistance wire. In my pic I see a small nub of pink wire on the black plug. Was there at one time a female plug attached at that pink nub? I don't understand why the original owner had done this poor modification, thinking this might be why I am intermittently loosing spark.

[shelbydoug]

Originally there was a bullet connector on the tach end of the pink and a molded 90 degree stud mounted boot for the coil.

The reistor wire reduces the 12v supplied through the ignition switch, through the tach to the coil.

Some say the yellow top is 6v. Some 9v. The point is it isn't 12v.

The tach has difficulty reading accurately at 12v and should feed to the full pink resistor wire. I believe if you measure it with a multi-meter it will be around 1.6 ohms. So if you modify that wire, you want to come close  to the 1.6 for the tachs sake.

You run 12v from the ignition switch to the + terminal on the coil, provided you are using a 12v coil. That is the hookup for adapting the Petronix.

Trace the wires spliced into your pink wire. They were probably trying to get a 12v power source and didn't realize there wasn't 12v in that wire. Remove them from the pink and if they need 12v, run a 12v off of the back of the ignition switch to them.

Incidentally, the insturments have the voltage reduced to them also to 5v. The tach is wired independently though.

[Horsman]

Better pic.  Trying to figure out what happened here.

I have 12V going directly to the Pertronix, made a jumper harness that plugs in between the ignition switch and the tachometer connector.

[shelbydoug]

Better pic. 

I have 12V going directly to the Pertronix, made a jumper harness that plugs in between the ignition switch and the tachometer connector.

Sure but the tach has to be all by itself without anything spliced or attached to it.

The pink wire needs to be by itself also since it now is the tach sensor wire. You can't splice anything into it.

[Horsman]

Better pic. 

I have 12V going directly to the Pertronix, made a jumper harness that plugs in between the ignition switch and the tachometer connector.

Sure but the tach has to be all by itself without anything spliced or attached to it.

The pink wire needs to be by itself also since it now is the tach sensor wire. You can't splice anything into it.

Please take a look at my first picture. The bottom left corner of the picture shows the male end of the resistance wire. That wire goes directly to the tachometer on the opposite end. The original resistance wire has never been cut. The added orange wire with the female bullet connector end was soldered to that red wire for some reason, my resistance wire was plugged into that orange wires female end.  If you look close you can see a small portion of pink wire that has been cut off the black connector in the pic. I guess I'm trying to figure out how the male side of the resistance wire plugged in somewhere in the kick panel on the driver side. Was there a female bullet connector that was chopped off at that small nub that was accepting the male end of the resistance wire?

[shelbydoug]

I'm having a hard timie following what is in the pictures.

All I can tell you is what I have already posted.

The output/resitance wire must be undisturbed to the coil +.

You can splice in to the switch 12v output which connects with a bullet connector to the tach input.


Why the other wires were spliced in, I have no idea. That is for you to decide. Sorry. Wish I could help more, but I can't.

[roddster]

  Just another possibility:  Somebody cut in a hidden ignition shut off/ground switch.