Why old fuel is bad for your lawn mower

By having your mower inspected each year before you need it, you can ensure it will run properly once you’re ready to start it up and extend its life. (Photo by Grant Smith)

By having your mower inspected each year before you need it, you can ensure it will run properly once you’re ready to start it up and extend its life. (Photo by Grant Smith)

Dear Angie: I purchased a new lawn mower last summer. Now, after sitting in the garage for the winter, it won’t start. It appears that no fuel is reaching the carburetor. If I spray starter fluid or put gas in the carburetor, it will start but then just shuts down. What could be the problem? – R.D. Wilmington, DE.

Dear R.D.: This is actually a common issue many homeowners face when they bring out their mowers for that first mow of the year. It’s often the result of ethanol-based fuel that sits in the tank over a period of time and essentially turns into varnish. The bad fuel can gel up, causing clogs in the fuel line and carburetor. When you go to fire up the mower that first time and the bad fuel reaches the carburetor, the mower will often start and run for a few seconds before dying.

In speaking with lawn mower maintenance professionals, I've learned this is something they see every year and for them, it’s an easy and inexpensive repair. Typically, starting at about $50, depending on your mower type, you can have a professional inspection and tune-up of your mower. Most pros recommend an annual tune up, which usually includes inspecting the carburetor and cleaning it if necessary, checking cables and belts, changing the spark plug, air filter and oil, sharpening the blades and cleaning the mower.

By having your mower inspected each year before you need it, you can ensure it will run properly once you’re ready to start it up and extend its life. Plus, your lawn will look better. A mower with dull blades, for example, can damage grass by tearing it out rather than cutting it evenly.

If you’re mechanically inclined, you could attempt to drain the old fuel in a safe and legal manner – an authorized waste recycling center and many automotive parts stores will take your old gas and oil – and then remove, disassemble and clean the carburetor yourself.  After you’ve reassembled the carburetor, put fresh gas in the mower and that often will do the trick. Putting a carburetor back together can be tricky with several small parts, though, so unless you’re experienced, I recommend leaving this to a pro or you could just cost yourself more money in the long run with additional repairs.

Lawn mower pros recommend adding fuel stabilizer to your fuel at each fill-up, which will help keep the fuel and carburetor clean throughout the season.

To prevent this problem from occurring in the future, be sure your mower is completely drained of fuel during the months it’s not in use. If it does have fuel in it, be sure to add the recommended level of fuel stabilizer to it to help keep the gas from gelling. This will only work with fuel that is still good. Adding a stabilizer to gas that has sat in the tank for an extended time won’t do any good.

Angie’s List collects about 65,000 consumer reviews each month covering more than 550 home and health services. Angie Hicks compiles the best advice from the most highly rated service pros on Angie’s List to answer your questions. Ask Angie your question at askangie@angieslist.com


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