Bad ignition switch?

Rebuilt the carb. Runs great in all aspects. So that could just be coincidental.

Twice now while idling smooth as can be, it has shut off. Just as if the ignition switch turned off. Starts right back up. No other issues.

The switch is old and a bit balky. Not as “smooth” as it once was. Could this witch be the culprit? Thx

No enough information to tell anything. What kind of car are you working on?

It’s possible. I had a 66 Mustang that would stall and backfire when going more than 65 mph for any extended period of time. Eventually, the stall and backfiring got more and more frequent to where it was undrivable.

Turns out, it was a bad ignition switch that was heating up and shorting out. Sounds like yours might be worn and vibrating out of the run position.

Try the primary circuit test.



Sorry 1970 Mercury Cougar. Owned it 40 years. It’s done a lot of stuff, but it never did this.

The XR7 has a factory tach inline with the ignition. If it fails the car dies. Do you have an XR7?

Not XR7. Standard coupe. 351W. Fixed steering column

Stock ignition? (points)

Electronic ignition. Mallory Unilite distributor. MSD Blaster 2 coil. I would prefer not throwing new parts on without knowing what is failing. But there’s no real way to test the electronic ignition. Seems like I just need to drive it locally until it finally fails.

I will add that the other day while the car was running, I did jiggle the key to “test” the ignition switch. As the key moved towards OFF, the alternator light came on and the radio turned off, but the car still ran.

Electronic ignition. Mallory Unilite distributor, exact same as mine, same problem, searched long for that one. In my case the electronic ignition module was bad. And there is a test for that.
http://www.manualsdir.com/manuals/337302/mallory-ignition-mallory-unilite-test-procedure-mallory-unilite-test-procedure-605.html

Check it out, highly likely that is also your problem.

Thx. I will check it out.

It passed the test, but that really only means it was ok when I checked it. So far 99% of the time, the module works.

This will be a good test when the car won’t start.