It's probably bad gas. Gas degrades while sitting around, especially while sitting in a can in a garage. In the winter, gas will stay fresh for about a week or so, in the summer, maybe a month. Small motors are real finiky about gas, unlike most cars and trucks. Here's what I would do. Empty the tank, and pull the spark plug. Pull the starter a few times to get rid of anything in the chamber. Install the spark plug and put in fresh gas. Take off your air filter and spray in a bit of starting fluid or pour in about a cap full of Sea Foam. Let the mower sit 5-10 minutes. When it starts, it will smoke VERY badly for the first minute or so. This is normal, so don't be worried, but make sure you do it outside. It's just built up carbon deposits being cleaned and burnt off because of the sea foam you put in it. Use as normal after it stops smoking, with will take a few moments. Also, I'd recommend putting a bit of Sea Foam or Sta-Bil in your gas can when you fill it up to keep things fresh.
Tom, September 2009
