My mother-in-law just had the same problem. The solution was to drain some of the oil. It will smoke if there is too much oil in the crankcase, and it may damage your engine as well.
Time to rebuild the carb and replace the float needle and seat. If you have a Tecumseh engine the part number is 631021B. After doing so, do any oil change. Engine will smoke onstartup, but should clear in about five minutes.
