Checking the Air Circulation Shutoff Valve

With a defective air circulation shut-off valve, the engine does not start or runs unevenly at idle.

Turn on the ignition.

Disconnect and connect the wire to the air circulation shut-off valve. At the same time, valve clicks should be heard.

If clicks are not heard, then either the wire is broken, or poor contact with the ground between the carburetor or intake pipe and the engine, or the valve is defective.