Engine won't stop running when key turned off.

Replaced alternator which was damaged by turning battery off while engine was running. Replaced alternator. Turned key on and started engine. Runs perfectly. Turned key off but engine keeps running. Key switch works correctly. Battery voltage applied to coil when key turned on, alternator voltage appears at coil after engine started. Anyone have any suggestions as to why the engine worn't turn off when key turned off?

Re: Engine won't stop running when key turned off.

What are we working on?

Re: Engine won't stop running when key turned off.

Just found out there is supposed to be a diode (resistor) in the Field circuit. Does it go between the field terminal and the battery without going through the ignition switch or does the field get disconnected by the ignition swith?

Re: Engine won't stop running when key turned off.

You keep asking questions, when are you going to tell us what engine you are working on. We aren't mind readers.

Re: Engine won't stop running when key turned off.

Volva Penta conversion of a chevy 350 small block in a 1976 Chris Craft Lancer with outdrive. The alternator is a 3 wire unit driven by the main belt.

Re: Engine won't stop running when key turned off.

In my case, the key switch was the culprit.
http://72land-n-sea.blogspot.com/2011/08/found-phantom-start-gremlin.html?m=1

Also, on my small block Chevy, there is a wire from the starter to the coil that bypassed the resistor when the starter is cranking. Might try disconnecting it after you get her running and see if the key will shut it off then.

Re: Engine won't stop running when key turned off.

Look at the starter solenoid, and see if the main battery terminal is touching the outside small terminal. This would keep power on the ignition circuit if it's touching.
That engine did have a resistor on the alternator, looks like the picture below. Did you see it on your old alternator when you took it off?

Re: Engine won't stop running when key turned off.

Yep, I have that resistor device on my alternator but when I put an ohmeter on it it was a dead short. Just bought another from volvo which has a measurable resistance when checked with an ohmeter but have not yet installed it. Too hot to work on the boat.

Re: Engine won't stop running when key turned off.

I have a 1984 aq125a with this scenario, I have been reading here for years but finally joined to get help with this nagging problem. The boat I recently purchased had been hacked in every electrical area however I did not find the =gizmo= in the bilge as I did some other parts and the wire feeding the coil is shared with a wire to the alternator that is also shared to the starter solenoid.
My question is the value of the resistor or is this really a blocking diode to prevent the cranking motor from being activated once the motor is already running?
I have almost solved all the other problems thanx to patiently reading here, soon I will dip the drive into a water tank before the maiden voyage after removing 75lbs of black tape concealing the savage mechanics tricks.

Re: Engine won't stop running when key turned off.

leakywire said:

I have a 1984 aq125a with this scenario, I have been reading here for years but finally joined to get help with this nagging problem. The boat I recently purchased had been hacked in every electrical area however I did not find the =gizmo= in the bilge as I did some other parts and the wire feeding the coil is shared with a wire to the alternator that is also shared to the starter solenoid.
My question is the value of the resistor or is this really a blocking diode to prevent the cranking motor from being activated once the motor is already running?
I have almost solved all the other problems thanx to patiently reading here, soon I will dip the drive into a water tank before the maiden voyage after removing 75lbs of black tape concealing the savage mechanics tricks.

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Re: Engine won't stop running when key turned off.

Sorry Bond-o, you can erase the post as I made a new thread