Electrical shock from engine

[MillWeld]

When I turn off my 16 HP 2 cylinder Kohler I get a shock to my fingers from the ignition key. Only happen when shutting down, not starting or running. Bad ignition module? Any advice on replacing/repair? Engine is on a portable sawmill.
Bob

 

[Craig Clayton]

I assume your engine has a 12 battery for starting the engine so that should not give you a mild shock on the 12 volt side of the system.
The high voltage that is made for the spark is created in the coils through the plug wire across the spark plug and then the engine frame.
When you stop the engine there will be a final collaspe of the coils and that last spike is what must be giving you the mild shock..
Is the engine mounted in rubber and not bonded to the frame.
Could you have a static build up on the rubber drive wheels.

This probabily is not much help.

Craig Clayton

 

[MillWeld]

When you stop the engine there will be a final collaspe of the coils and that last spike is what must be giving you the mild shock..
Craig Clayton

I think that is the case.

I get a pretty strong tingle at my fingers so it is not the 12 V battery. Engine is bolted to the frame and drive wheels are crowned steel, not rubber tired.
Bob

 

[SimS]

Check that the ignition switch has a good mounting/ground contact. My bet/guess is that when you turn the switch to OFF, it grounds the ignition system. If the switch is not well grounded, the electrons want to go through your fingers to ground. My 2 cents.

SimS

 

[J_J]

SimS is right. I had this happen this happen to me as I was testing a switch. You have to ground the switch body because I believe the white wire is the grounding wire to the switch, and it grounds out the High Voltage.

This diagram is similar. It is the white switch.

Recent image by Restrorob on Photobucket

The HV goes to pin M, and if the switch is not grounded, the voltage goes through you.

If you installed the wrong switch, then you will get the shock.

They make many variations of that switch.

You need the one that the terminal does directly to the metal of the switch.

If the switch is mounted on a non conducting item like plastic, etc, add a wire to the switch under the switch nut and run that wire to ground.

 

[BobRip]

SimS is right. I had this happen this happen to me as I was testing a switch. You have to ground the switch body because I believe the white wire is the grounding wire to the switch, and it grounds out the High Voltage.

This diagram is similar. It is the white switch.

Recent image by Restrorob on Photobucket

The HV goes to pin M, and if the switch is not grounded, the voltage goes through you.

If you installed the wrong, then you will get the shock.

They make many variations of that switch.

You need the one that the terminal does directly to the metal of the switch.

If the switch is mounted on a non conducting item like plastic, etc, add a wire to the switch under the switch nut and run that wire to ground.

My thoughts exactly. Make sure the switch is grounded.

 

[MillWeld]

Everybody is right on target!!

My problems started when I removed the ignition switch to get to the throttle lever to insert new friction washers in the lever handle. When I reinstalled the switch ground I inserted the ground wire between the plastic cowl and an apparently painted steel surface making a very poor ground connection. Thanks to your alerts about a ground problem I re-examined what I had done and discovered my error. I re-installed the ground wire so the mounting bolt head made contact with the ground wire and a good ground was re-established to the engine block. Started the engine, shut it down and NO shock.
Thanks,
Bob

 

[jonyyuma]

JJ, I like your new photo, with your red hat. Do you do public appearances?

 

[Don87]

Everybody is right on target!!

My problems started when I removed the ignition switch to get to the throttle lever to insert new friction washers in the lever handle. When I reinstalled the switch ground I inserted the ground wire between the plastic cowl and an apparently painted steel surface making a very poor ground connection. Thanks to your alerts about a ground problem I re-examined what I had done and discovered my error. I re-installed the ground wire so the mounting bolt head made contact with the ground wire and a good ground was re-established to the engine block. Started the engine, shut it down and NO shock.
Thanks,
Bob

Shoulda left it the way it was.

12 volt electrical shock is supposed to help if bitten by a Rattlesnake.

 

[MillWeld]

QUOTE=Don87;2635007]Shoulda left it the way it was.
/QUOTE]

I couldn't. The the old friction washers were broken and would not hold the throttle in position; it would slowly slide back to about 2200 rpm.