JCPress - hi, I'm assuming the mower won't start at this point. I've left mine full of gas over the winter before (including this past winter) and it started on the first pull. (I leave mine on my screened-in porch, and it gets cold and - this year - snow on it.) If the gas tank was totally full, then water condensation shouldn't have gotten into the engine.

You'll want to totally drain the gas tank and dispose of the gas you remove. Then, pull the spark plug and check it to make sure it's not gummed up. (That's the problem the old gas will cause - components in it break down and can coat some surfaces in the engine with a gummy or varnish-like substance.) Refill the gas tank with new, fresh gas - I'd recommend only about 1/4-tank in case you have to dump it again - and I'd add a little "dry gas" like you'd use for your car when you have water in the gas. Prime the carburetor and give it a few pulls with the throttle/speed control in the START or fast position. Good luck!

In the fall, you can go to places like Wal-Mart, ***** , etc. and get stuff to stabilize your leftover gas. You can normally find small packets that are sized for small gas cans or you can find larger amounts that require you to measure and mix. They come with complete directions. I hope this helps some - regards! Jim D/Heathsville, VA

Thanks. That was very helpful. I haven't tried to start the engine yet - I'm afraid that it'll screw things up even more. You suggest draining the gas from the engine. Would they sell a pump or some sort of siphon at the local hardware store? Or should I do it the old-fashioned way with a tube and some suction?

Try and start it. If it starts just add more gas as required and change the oil. You probably din't change the oil last year either.
Sharpen the blade also. If it is self propelled you might need to grease the drive wheels also.

JCPress - hi, your engine and carburetor will have very little gas in them. You'd want to drain the gas tank, which is easy enough to do. You should be able to remove the gas line from where it attaches to the carburetor, and drain it into a container of some type. Just make sure it's large enough to hold all the gas from the tank! On my push mower, I can actually remove the tank from the mower by simply sliding it upwards off its mounting brackets - I pinch the gas line shut, pull the tank up, and drain it into my gas can. (I put the old gas into my wife's car and then top off the car's gas tank...mixing that quart of old gas with about 14 gallons of fresh gas hasn't hurt it. I can't put the gas in my car's tank...I drive a VW with a diesel engine...)

Joed is correct that you can try and start it. The worst thing you'd do is possibly flood it, and you'd have to let it sit a while before trying again. As I said, I left mine on my back porch all winter long...we had probably 4 feet of snow over the season and several weeks of below freezing temps. The gas tank was totally full. I'd changed the spark plug and the oil last fall, so I knew they were good to go. I put a new blade (old one was beyond sharpening anymore) and new air filter on it and primed the carb. It cranked over on the first pull...I've used it 3 times now and no problems at all.

I hope this helps some - good luck! Jim D/Heathsville, VA

Supposedly, what happens is that gas separates and can cause excessive varnish buiildup in the carburator.

I never drain my gas out and it always starts the next year. Going on ten - twelve years now. Maybe I'm just lucky. Maybe the advice to drain is overkill on preventive maintainance.

Piffin is right. Usually, you'll have no problem. Just try to start it as if it hasn't been used for a few weeks.

Next year, either drain it or use some stabilizer when you put it away for the winter.

I did the same thing with my Mantis tiller. 2 cycles are really problematic with gumming up. It would start but wouldn't go to full power. On a suggestion from a friend I put some Neutra Fuel Stabilizer in the fuel tank and started it. Although it smokes a bit from all the gunk being burned thru the engine it runs like a top. Neutra is manufactured by Schaeffer's. Disclaimer: I do not have any business connection what-so-ever with Schaeffer's. I've started using it in all my 2 cycle motors (lawn mower, boat, etc)

Quick follow-up here. Thanks again for all the advice. Got me some fresh gas and a new spark plug...and, the engine started! Lawn is now manageable.