Smell it before you pull the cord

The fastest way to tell if last year’s fuel has gone bad is to smell it. If it smells sour, varnishy, or like paint thinner, don’t try to start the saw.

Gasoline degrades over winter, especially the ethanol stuff. It oxidizes, picks up water, and turns into a gum that will coat your carburetor the moment you pull the starter. You don’t need to take the carb apart to check. Just open the fuel cap and take a whiff. Or pour a little into a clear jar. Look for a dark, cloudy color, layers of separation, or tiny water beads. If it looks or smells off, it’s bad. Period.

If it seems borderline, drain it anyway. Fresh mixed fuel is cheap; cleaning a varnished carburetor is not. Also, starting it with bad fuel can pull that varnish into the jetting and make the problem worse, not better. When in doubt, dump it.

Your chainsaw isn’t sentimental. Give it fresh fuel and get back to work.