kohler won't stop

[Gary Davis]

If he has the kohler command 25 like mine the only shut of is the fuel solenoid turn the key off the valve shuts the fuel of and the engine dies, if the vaulve only closes part way and not completely, and,, as long as the engine gets gas it will run on one cylender remember I have the same mill and engine and had the same problem, being it is the easiest part to check that is where I would start.  the woodmizer techs that I have talked to always gave me good information, If you believe woodmizer is wrong go argue with them if you want to keep chasing rabbits  go ahead I am done

[47sawdust]

The motor on my 1997 WM Lt30 is shut off by the fuel solenoid only.

[curved-wood]

Right now I am slow to do the proper testing du to an overload on the cedar demand. Right now I am just unpluging the spark plugs to shut down the engine. I still have my old motor so change the solenoid fuel is with no cost beside the time to do it which I dont have right now. At least business is strong
Thanks for all the comments, I am learning a lot

[VooDooChikin04]

Hind sight it seems so obvious, engine shuts down with fuel solenoid.  Engine not shutting down with key off..  fuel solenoid must be allowing fuel through. 

[pineywoods]

It ain't just kohler. My mill has a 25 hp kawasaki and there is a fuel shutoff solenoid in the carb. Larger briggs engine on neighbors norwood also has one.

[dgdrls]

Based on the OP having a CH 730S engine,
http://www.kohlerengines.com/engines/onlinecatalog/pdf/sm_24_690_06.pdf

Per the service manual for CH18-CH25, CH620-CH730, CH740, CH750   edited (the S designation means electric starter, not pertinent to)
Fixed Ignition System
● 1 kill switch (or key switch) which grounds modules to stop engine.

Smart-Spark TM Advance Ignition System
Digital Spark Advance Ignition (DSAI) System

● 1 kill switch (or key switch) which grounds spark advance module to stop engine.

Could the fuel solenoid/anti after-fire valve be bad, sure it could, but its not there to starve the engine to stop it
grounding the ignition stops it.  

D

[Remle]

For any one whom believes that the fuel solenoid stops the engine, tell me why only one cylinder continues to fire multiple times in a row and the other cylinder doesn't fire, both draw fuel from the same place.

[Ben Cut-wright]

WoodMizer utilizes wiring schemes on their sawmills that often have to be made compatible with the particular engine option used.  NO matter, there are only so many ways to turn this engine OFF.   There are schemes where the ignition switch provides battery voltage to the ignition, and schemes whereby the ignition switch grounds the magneto circuit.  Reviewing many wiring diagrams for LT30 and lT40 mills in the OP's year range did not reveal other *standalone methods.


The specs the OP provided, the descriptions he gave of the fault, and the results he attained by removing the spark plug wires one at a time,  give much credence to the hypothesis that secondary ignition continues to provide spark....on one cylinder....at key off. 


Fuel cut solenoids are easy to replace, but they are pricey components to throw at a repair without a sound diagnosis. 

[Remle]

For any one whom believes that the fuel solenoid stops the engine, tell me why only one cylinder continues to fire multiple times in a row and the other cylinder doesn't fire, both draw fuel from the same place.

Well gents it's a day later. Yesterday when I posted their were 1945 views, today their are 1976 views with no one  offering up an answer to the question. So here is the answer, IMHO, the one cylinder is shut down by the kill circuit and the kill circuit is compromised or ignition module to the one firing is defective. Some have offered up that the OP should just pull the plug wire to stop the engine, as a temporary soultion. It seem he agrees with this, how ever, IMHO, it introduces a new set of problems. Their are 4 that I can think of off the top of my head, 1) each cycle fuel is being drawn in to the non firing cylinder, wetting the plug/washing down the cylinder walls. 2) it empties the carb. 3) it's putting way more stress on the rod in the firing cylinder, it's now carrying the load from the non firing cylinder by pushing it through the intake, compression and exhaust strokes as well as it's own. 4) restarting the engine with a wet plug/washed cylinder and refilling the carb means more revolutions necessary to start the engine are required putting additional strain on the starter. Now I cannot eliminate all of these problems, but the 2 most detrimental  # 1 and 3 can be avoided. If he, instead of shutting off the key switch and pulling the plug wire, were to leave the key on, so both cylinder continue to fire and pull the feed to the carb relay, it will eventually drain the carb and stop in a more controlled way. IMHO the " clacking " he reported would stop. The controlled way, IMHO, is why the manufacture added the carb relay, tied it to the oil pressure sensor, as an emergency way to shut down the engine in case of lost oil pressure and not the normal system to stop the engine, that is the function of the heavily debated kill wire. 
Now one more thing to rember, turn off the key after the engine stops to prevent the movement of the rest of the functions activated by the key and of coarse plug the carb solenoid wire back in before trying to restart the engine.
 Again these are just my opinions, so take them or leave them as you see fit.
 

[luap]

Using the link provided by dgdrls and looking in the manual, it identifies a white wire from each ignition module as the kill wire. These two wires are connected to a single white wire that goes to the key switch. A black wire goes from the key switch to ground. Possible broken white wire or connection on the module for the cylinder that keeps firing or a problem where connection is made with single wire to keyswitch. This has been a long thread with good information and a stopgap solution is no fix. Having worked my career in maintenance this would irritate me no end and would be fixed right regardless of what the production manager demanded.

[sawwood]

 Not sure if the kohler  engine is the same but we have a Farris riding mower that has a kohler motor.

 After I over hauled the motor you could not stop it from running. Talked to a farris dealer and he said

 coils have a single wire that grounds them to kill the motor. We bought some off ebay and that fixed
 
 the trouble but it didn't run to good. So we bought coils from the farris dealer, real kohler coils and now

 it runs good and stops when we turn it off. PS just buy real kohler parts.

 Sawwood

[Ben Cut-wright]

Not sure if the kohler  engine is the same but we have a Farris riding mower that has a kohler motor.

After I over hauled the motor you could not stop it from running. Talked to a farris dealer and he said

coils have a single wire that grounds them to kill the motor. We bought some off ebay and that fixed

the trouble but it didn't run to good. So we bought coils from the farris dealer, real kohler coils and now

it runs good and stops when we turn it off. PS just buy real kohler parts.

Sawwood

Thanks for relating your similar experience.   Do you recall why this problem appeared after the engine was overhauled?  What changed or what component-s  failed that were operating properly before the engine repairs?  Did both coils continue to provide spark or, like the OP's engine, run on one cylinder?
  
OEM parts are often the best choice.  Do you recall how "didn't run too good with ebay parts" was diagnosed as faulty coils?

Why made the overhaul necessary?

Pardon all the questions, thanks for any answers you may provide.

[sawwood]

 Not sure why the trouble started after overhauled. Yes both coils provided spark and the
 ebay coils would some times make the engine backfire. We had to overhaul the engine
 because one cylinder the piston rings had broken and there was a loss of comp. After we
 installed the factory coils it ran better and no back fire. The old coils the kill circuit was what
 was bad and it would not stop when the key was turned off. Hope this helps.

 Sawwood