[ccollins0601]

Hi all,
I got a Cub Cadet 1200 last fall that I've been using for snow plowing & hoping to use for mowing in the spring.

The problem is when under heavy load it tends to stall or quit. It occurs after running about 10 minutes and especially when in high gear pushing snow. The engine will go from sounding strong to muffled and slow.

At that point if I don't play with the throttle and put it in neutral it will usually die. Sometimes it will backfire and/or spit a lot of black smoke out the exhaust. Every time I pull the plug it is black & oily. Once this happens once it tends to happen over & over again until I let it sit a while.

So far I have:
Replaced points & condenser
Installed a new carburetor
Tried multiple spark plugs
Checked the spark (strong & blue)
Changed oil
Checked all the wiring
Messed with the carb adjustment screws more times than I care to
Added mystery oil to the gas

I've learned a lot about these engines but it's starting to get a bit frustrating. Not sure what to do next. Any suggestions?