Please post the model numbers off the engine. Is this the courage engine. If so does it have the heat shield behind the carb bowl. There was a problem with the position of the muffler when MTD moved the muffler closer to the engine, that caused head damage to the fuel solenoid, even burning the insulation of the wire in some cases.
Kohler blamed it on the no head shield on the muffler causing heat damage to the solenoid. MTD said that the Kohler voltage regulator was overcharging, and burning out the solenoid. the bottom line came down to neither company would pay warranty repairs, and the customer had to fork out the money to repair a new mower.