[Richard and Rhonda]

My guess about the gremlin goes like this. Since the engine will turn over but not crank, and will run but not turn off, that the fuel shut off solenoid is either faulty or wired incorrectly.

If you can get it to turn over, but not fire from the ignition key, it means the engine is not getting fuel.

When you turn off the ignition key, but the engine keeps running that means the key did not turn off the fuel. We have to think differently about engines when talking diesel.

Using the stop toggle in the back could be activating and deactivating the solenoid.

Do you have a helper, so that you can watch the action of the solenoid, or better yet put a voltmeter on it while you try the different switch configurations?