How can you tell if your fuel is bad?

Many folks don’t know that gasoline can begin to degrade and oxidize (go stale) in as little as 30 days after it is pumped—and that’s assuming it was fairly fresh when you pumped it. Regardless, you’re now wondering if you blew it and your fuel is now stale. (Not sure what “stale” gasoline is? Take a look at our post from guest author Todd Matvick of Lube-Tech.) But how can you be sure?

You could try and start your engine. If it sputters and dies or refuses to catch at all, bad fuel could be the culprit. But that’s not necessarily the problem, it could be something else, like a worn-out spark plug.

Better to take AutoBlog’s advice and pour some of your gas into a clear glass container and compare it to a freshly pumped sample. Safely getting a sample from your gas tank can be achieved by following the first two steps in our instructions on safely cleaning your fuel tank. (As always, consult your operator’s manual before performing any maintenance.) You’ll notice that older gasoline is darker than the fresh fuel. This is due to oxidation, which can occur after your fuel is pumped. Also, if there is any sediment at the bottom of the container or you see water separation, you have bad fuel.

We’d love to tell you that there’s a quick “fix” for bad fuel, but there isn’t. It’s a bit like spoiled milk. Once it’s gone bad, there’s no reversing it. Once fuel has begun to degrade and oxidize, there is nothing you can do but drain the fuel, clean the tank, if needed, and start fresh. Additionally, you may need to clean your carburetor as the bad fuel will likely have gummed and clogged it up. To help, Briggs & Stratton has an easy to follow guide for cleaning your small engine carburetor here or find a local certified Briggs & Stratton dealer here.

If your fuel has gone bad, just file it under “lessons learned,” clean it up and make a note to yourself to properly store your snow blower in the spring (or mower engine in the fall).

Fill Your Can, Treat Your Fuel:

While storage is important for keeping fuel fresh during the offseason, using a fuel stabilizer or treatment year-round is the best way to keep your fuel fresh and protect your engine. The easiest way to treat your fuel is to add fuel stabilizer to your gas can when you fill it at the pump.

NOTICE: Customer service questions are not monitored via the blog. If you need assistance with your Briggs & Stratton engine or power equipment, please contact our Answer Center or post your question to our User Community.