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Small Engines (Lawn Mowers, etc.)/pull start handle jerks out of my hand when trying to start lawnmower


Hi Eric,
My uncle has a 5hp MTD lawn mower that when he tries starting, jerks the pull rope handle out of his hand. He told me he recently installed a new blade and was able start and mow the grass without a problem. Today he says it won't start and jerks the rope out of his hand. I don't know if he has hit anything, or if it is a timing issue, sheared flywheel or blade key issue? He said it has spark, he must have felt it because he can't see it (89 years old).  Any help would be appreciated.

John C

Only 2 things cause this condition.

1)  Loose blade or blade adapter
2)  Sheared flywheel key

One other possibility is oil in the cylinder if the mower was tilted.  I would remove the spark plug and check to make the blade is super tight.  Leave the spark plug out and pull the string to see if any oil comes out the spark plug hole.  

Check the oil level to make sure it is correct.

Try to start.

If it still jerks then remove the flywheel nut/clutch and see if the key is aligned with the crankshaft and flywheel.  You will need and impact gun or a flywheel holder to remove the nut/clutch.

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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