i bought a new 8 hp tecumseh engine for my snow blower in 2006. it ran great until 2011. it started hunting and popping out the muffler(afterburn). in 2011 i cooked and cleaned the carb but it made no difference. in 2012 i ground the valves and bought a new carb. it still doesn't run right. in 2013 i bought another new carb and a new coil, i still can't get it to run smoothly. seems to take a lot of gas, smells like it is getting too much gas but the carb is not adjustable. still is hunting and popping out the muffler. don't know what to try next. runs better when it is warmer out but very poorly at 20 below. Less