how can i tell if my automatic choke is staying on when it shouldn't?

First disconnect your coil; it doesn't like to be idle and can overheat. Then remove the aircleaner so you can watch the choke. Turn on the ignition and watch. Does it eventually open?

The heating element in the coil is energized the entire time the ignition system is on. When you start a cold engine the choke spring in the heating element will be applying pressure to the choke plate to hold it closed. In addition the high-idle cam will be turned down so that the throttle is held open to keep the cold engine running.

The only factor in the opening of the choke is the amount of time the ignition system has been energized. If you were to go out and turn the ignition key to run without starting the engine and then wait a few minutes the choke will fully open. It doesn't matter if the engine is running or not. However, don't do it ;-) as you can overheat the ignition coil.

The easiest way to 'test' the choke is to go for a short drive. You should be able to open the hood with the engine running and see that the fast-idle cam(the metal plate with the steps on it, driver side of carb) is turned upwards all of the way. If it is still holding the throttle open then you need to find out what is hanging it up. Your problem could have a number of causes; it could be a mis-adjusted heating element, a binding fast idle cam, or a binding choke plate, or even having the throttle-stop screw turned in too far. None of these things are difficult to figure out or difficult to fix. Take off the air cleaner if you need to and see that the choke plate is standing vertically with a fully-warmed engine. If it isn't, you need to fix it.

Let us know what you find out.

Chris P.S. You should see 12 volts at the electrical connection on the choke with the ignition on. If you do not then start by fixing the electrical hookup for the choke.

Sorry Pico, but this method is not going to work. Pulling the B+ connection to the coil will also shut down the opening of the automatic choke.

Chris

You are right. OP - do it the running way Chris mentioned above.

I had a little intermittent binding in my auto-choke, resolved that issue. Here is how I tested it to be sure it is shutting off.

First tested it with the motor running and the air cleaner off and actually watch the choke slowly open. Rev the engine lightly a few times during, so the fast idle cam can step down and keep the engine in a "normal" rpm. You should see it stepping down and the choke opening in just a couple minutes or less. Then, because I'm obsessive........

Put the air cleaner back on and and wait a couple hours or so, to let things cool down a bit.

Now take it out on a short road test:

Start it and drive for a minute or two, set the parking brake, jump out and take a look, the fast idle cam should be stepping down and the choke opening (the cam can't step down if the choke is not opening) and you can see the little arm that actually attaches to the choke plate moving down as it opens, allowing the cam to "step down". Pull over about every minute and you will actually see how it progresses. The choke will/should be open (be off) in about 3 minutes give or take..