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1811 Surging at less than full load on engine

IH Cub Cadet Tractor Forum

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Well-known member
Aug 13, 2002
Chesterton, Indiana
Kevin Lindstedt
My M18 recently started surging when I turn off the PTO and set the throttle below full. I first noticed it after two hours of mowing, when I slowed the engine down to pull the lawn sweeper. I've read that surging can be caused by a blockage in the idle circuit of the carb, so I've taken the carb apart and soaked it in carb cleaner overnight. Blew out all passages and reassembled with new gaskets and float valve. At the same time, I put all new fuel lines on and a Kohler-branded fuel filter. I set the idle speed and mixture per the directions in the Kohler manual and all seemed good... until I mowed this past weekend. The surging is still there. I can not duplicate it in the garage running the tractor to operating temperature, it only crops up after an extended use. The carb is a non-adjustable Walbro. I can get an new aftermarket Kohler #26 carb for a reasonable amount, but would need to swap the throttle and choke shafts to get the correct linkages.

Questions - Before I give up on the Walbro, what have I overlooked? Any other possible causes for surging?

If I get the new carb, will the choke and throttle shafts interchange with the ones in the Walbro? Reading online it looks like this is the case, but I wanted to ask here as well.

Make sure the governor arm has not slipped on the shaft, effecting governor sensitivity. Easy to reset per the manual.

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