1650 Solenoid

Would a bad solenoid lead to a 1650 gas not shutting off when I turn the key off? It was not wanting to turn over well, and I found that the cable post was a little loose at the inner nut. I tightened this and it started turning over well, but the key will not shut it down now.

It's a delco 4 post solenoid, mounted on top of the starter. From outside in, one large post for the battery cable, two smaller ones that I didn't trace the wires too yet, and the large one on the inside that hooks to the starter feed.

The battery tests good, connections good there now. The key switch is basically new, but yes, they can fail. It shut it down fine before messing with the solenoid.

Thoughts appreciated!

Edit: The starter disengages with the key fine, the key will not kill the engine now. Thought I'd clarify that upon reading what I wrote!

Diagram I have of a 1650 shows a resistance wire from ?I? terminal of starter/ignition switch to power input to the coil (+ terminal for negative ground with alternator). This indicates a 6 volt or ?12 volt..external resistor required? coil with the resistance wire to match 12 volt system to 6 volt coil.

My diagram also shows a white wire coming off of the ?I? terminal of the starter solenoid (one of the two smaller posts). When starter is engaged this I terminal supplies 12 volts direct to the coil, bypassing the resistance wire, and giving a hotter starting spark. When starter disengages 12 volts is removed from I terminal of solenoid and coil again sees power from resistance wire.

Sounds like something in the solenoid is maintaining 12 volts at the I terminal when starter is disengaged.

Is there 12 volts at I terminal of start solenoid with switch off?

Disconnect wire from ?I? terminal on solenoid and see if it will shut down when key is turned off.

Other small terminal on solenoid (should be marked ?S?) is the starter activation voltage from start switch via neutral safety switch.

Large terminal on solenoid where battery connects should also have a charging wire from the ammeter.

Before jumping to conclusions it might be a good idea to check the stop solenoid to see if there is voltage on it when there should be none. Stop solenoids do stick/fail and the plunger neoprene seal can split.

Just wondering if you might have the delco alternator with the internal regulator. The switched feed wire to it needs a diode in it to keep it from back feeding on gas tractors. This is a well known problem.

RT