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Small Engines (Lawn Mowers, etc.)/engine shut-down after short operation time


I have a Kohler 22 HP (2 cylinder)in a Craftsman riding lawn mower that I purchased in circa 1994. It has operated very well for all those years until recently it has started to shut down after about one hour mowing. I have diagnosed it in my meager way as an ignition coil that overheats and the winding opens thermally. After a night in the barn it takes off like a new one until it fails again. The coil costs about 250 dollars so I'm told? I took the engine apart (flywheel etc.) and cleaned it well and it appears to be a waste of time but it was dirty and may help to promote heating. I am lost as to whether it would be the magneto windings inside the flywheel or the external coil that has the spark plugs wires extending from it.
Can you help? Also, does any one have a source for tested used parts  as I am reluctant to put that much money in such and old relic that I use for fence mower.

Not the magnets...never seen them go bad.

Coils/modules will sometimes fail when they get hot.  There are some expensive ignition module testers but these will not always work if the coil only fails when hot.

If I had to recommend an ignition tester it would be the Briggs & Stratton 19368 Ignition Tester.  They are fairly cheap and work well.

When the mower stops and refuses to start, just hop off, connect the tester, try to start and see if there is spark.  This is by far my best ignition testing tool as it has rarely ever failed to verify a module.  I can only remember 1 module that it did not work on as the engine would not accelerate.  It has proved weak coils numerous times no matter if they are cold or hot...the tester will help you diagnose the problem.

Have you replaced the spark plugs?  I'd have a new set on stand-by and change them as soon as the mower dies and refuses to start.
Let me know what you find.

Small Engines (Lawn Mowers, etc.)

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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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