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Small Engines (Lawn Mowers, etc.)/Kohler Engine runs rough when hot


I have a Kolher CV490s engine (on a Husq tractor) that seems to of lost power although it still starts fine. What is strange that when it gets hot it no longer likes to run at the detent (very rough, tries to stall). If I run it with a little less power I can keep it going but turning corners or going downhill while cause it to start to die (almost like you were flooding it for a second).  

Should I be looking at the carb or do you think there is a far more serious problem here ?  I have BTW checked all electrical connections that were obvious and do not see anything.

I would start with a carb cleaning.  Use compressed air from an air compressor and blow air through all the carb orifices.

I would also replace the spark plugs and check the valve clearances.

Did you download the service manual from Kohler's website?

How old is the mower?  Does the engine have a fuel pump?  Is the fuel tank venting properly?  I have had bad fuel caps but it's pretty rare.  You can usually check by leaving the fuel cap a little loose when the fuel level is less than 1/2 don't want fuel splashing out of the fuel tank or debris/dirt getting in the fuel tank.


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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