In the past few years small engine repair shops have been reporting an increase in problems with outdoor power equipment and landscape tools, such as leaf blowers, lawn mowers, and string trimmers. The culprit? Ethanol-blended gasoline.

Ethanol is a solvent that contributes to the deterioration of rubber gaskets, plastic nozzles, and aluminum — parts and materials common to small engines. Although heavy use and age contribute to wear and tear on internal components, ethanol speeds up the process.

In addition, ethanol contributes to deposits in fuel lines and carburetors, blocking fuel flow and causing engines to refuse to start.

In low concentrations, ethanol isn’t especially harmful to small engines. E10 ethanol blend, which is made up of 10% ethanol, is considered acceptable.

However, the EPA recently approved higher concentrations that are readily available at many gas station pumps: E15, a 15% blend, and E85 made for flex-fuel vehicles.

The reasoning, of course, is commendable: Using higher concentrations of domestically produced biofuels reduces gasoline consumption and yields better mileage for vehicles. Large, modern car and truck engines are designed to run ethanol-blended gas.

These higher concentrations, however, can wreak havoc on small engines. Small engine manufacturer Briggs & Stratton, for example, voids the warranty on its power equipment if you use gas with a higher concentration of ethanol than E10.

And E10 itself isn’t completely off the hook. Ethanol combines easily with water, meaning that it tends to grab and hold onto any moisture lingering in cans and fuel tanks. The result is an uneven fuel mixture that contains water — a bummer for engines.

The problem occurs when fuel cans and equipment containing old gas are left sitting around for months – chances increase that ethanol has made the fuel mixture potentially hazardous to your leaf blower and chain saw.

The potential frustration – and cost – to home owners is considerable. Briggs & Stratton estimates there are more than $50 billion worth of lawn mowers in garages all over the country.

Want to protect your investment, and avoid trips to the repair shop just when the leaves are falling? Here’s what to do:

• Use clean, fresh unleaded gasoline with a minimum of 87 octane.

• At the gas pump, check ethanol ratings carefully. Don’t use gas with a blend ratio higher than 10% (E10).

• Change fuel frequently. Gas that’s been sitting around for more than 60 days should be replaced with fresh gas.

• Gently slosh fuel containers to remix gas before adding fuel to small engines.

• Add a fuel stabilizer to your gas mixture. Ask your equipment dealer to recommend a product that’s formulated to reduce water absorption caused by ethanol gas.

• When storing equipment, such as your lawn mower over the winter, run the engine dry. Buy fresh gas next year.

Have you had a problem with your gas-powered leaf blower or trimmer? Was ethanol the culprit?