What do the spark plugs look like? Some times you can get coking to build up in the combustion chamber when trying to burn fuel and water at the same time and that could have caused one or more of the plugs to foul. Also, I am assuming you're now pumping new gas to it? Not some that has been sitting in a gas can for a while? The gas you get now a days doesn't have much of a shelf life so, I'm just checking.