I have a MTD Yard Machine model:287707 Type:1224E1 Code:09941220. The motor cranks fine and runs but it speeds up and slows down constantly (bested described as loping?). I have notice a arm on top of the carb that is attached to a spring and this is waht is moving back and forth. What causes this and how can I fix this issue? Any help will be greatly appreciated!!

TSR3901, April 2009

This is a symptom of a lean mixture - which in turn could be due to stale fuel. Use fresh fuel, and if you still have a problem (and you have checked for leaks as suggested), back out the main jet 1/4 turn at a time to see if that improves things.

phil_saunders(a)bigfoot.com

Phil Saunders, April 2009

Check for air leaks at the inlet manifold, also make sure crank case breathers are clear, and air filter. This is only general advice though sorry. hope it helps.

stu, April 2009