Diagnosing starter problems

Question:

I am in the process of trying to start my 1962 Corvair for the first time. I put in a rebuilt starter and new ignition switch. I have also put in new wiring from the starter to solenoid. I can get the engine to turn over, but when I turn the ignition off the motor keeps turning. I have to remove a battery cable to shut off. Can you help me with this problem?

Answer:

If the starter, solenoid and ignition switch are working properly, this is very likely a wiring problem. There are a couple of missing bits of information that would have helped with the solution to your problem. The first would be: have you upgraded the system to an alternator? If so, it is possible that you wired it up wrong. Go back over the wiring diagram supplied with the alternator to make sure it is hooked up correctly.

Another question would be: Does the starter resume cranking when you hook the battery back up with the key in the “off” position? That would indicate that you have inadvertently “hot-wired” your car, by by-passing the ignition switch. That could have happened if you wired the starter into the hot lead from the battery.

Otherwise, for the starter to continue operating after turning off the engine the solenoid must be engaged, which could happen in two ways: Either mechanically, in which case the solenoid would jam in the energized position, perhaps due to being incorrectly adjusted, damaged or corroded, or the problem could be electrical, such as wiring the starter to either the accessory or ignition terminals on the ignition switch. That would make the starter run any time the key is on, even without being turned to the START position. But when the key is turned off, the starter motor would stop.

Wired correctly the system works like this:

* With the key in OFF position none of the ignition switch terminals are hot except BAT, which comes from the battery.

* Turn the key to ACC and only the ACC terminal is hot.

* Turn the key to ON and the IGN and ACC terminals are both hot.

* Turn the key to START and the S terminal is hot, causing the starter to crank the engine.

* Release the key, and it relaxes to the ON position. The S terminal is no longer hot, but IGN and ACC are both hot.

You can check the solenoid by energizing it to see if it kicks in and then releases, and you do that by grounding it against the chassis, and then touching a wire from the battery to its terminal. If the solenoid is working as it should, then make sure you have wired the system correctly according to the schematic in your shop manual. We know the starter is good because it turns over as it should.