I recently had trouble with the throttle on a two-stroke engine. It ran fine once I fixed that, but I didn't have time to till right then, so I turned the thing off.
It rained the other day, so I put a tarp over the tiller. It may have gotten a bit damp.
Then, after the rain, I tried to start it again. No luck. The engine turns over with the pull-cord and the spark plug sparks. It makes a slightly different sound when I close the choke. And I can definitely smell gas when I try it with the choke open, so it's getting fuel. The air filter is a little dirty but no worse than it was the other day when I started it successfully on the first or second pull.
Any ideas? It's definitely got the right kind of gas/oil mixture, though I do have to use 10% ethanol (only option).