William Gray was on a routine fishing trip to Arkansas’ scenic Lake Chicot about three years ago when his bass boat needed a fill-up.

After a day’s haul with co-workers in the Grand Gulf Bass Club, the avid duck hunter and bass fisherman noticed the ethanol stickers on gas pumps there and headed across the river to Greenville. But time was short, and he filled tanks feeding the boat’s 200 horsepower Mercury engine with gas that had been blended with 10 percent ethanol.

“I heard a station in Greenville had straight gas, but I just took it to the next one I could find. Within 10 minutes, my engine started failing,” Gray said. “(The ethanol) had crystallized and crumbled and had clogged my fuel line, and I had to tear out all of the fuel system.”

Gray saved hundreds of dollars by repairing it himself, but his troubles with the motor are nothing new to marine shop owners, lawn mower mechanics and car enthusiasts familiar with the additive’s apparent incompatibility with small engines and older car engines. Familiarity about fuel systems might extend to the driving public soon because of a recent ruling on the grain alcohol that is now the dominant additive in most gasoline.

The Environmental Protection Agency ruled Jan. 21 that 15 percent ethanol blended with gasoline is safe for cars and light trucks made between 2001 and 2006, adding to a decision in October that the higher blend is safe for cars built since 2007. Maximum blends have been at 10 percent for about five years, including at most gas pumps in Mississippi.

While popular in farm states because most ethanol is made from corn and other grains, its opponents locally and elsewhere stress it leaves drivers of older, otherwise smooth-running vehicles in the cold and harms such small equipment as weed trimmers and boat motors.

“I have concerns about the unknown effects,” said Roy Pigg, whose owns a collection of classic Ford Mustangs from the 1960s to the early 1990s. “Things I’d heard about is it affects rubber components.”

“The bottom line is, all the small engines are not made to run on ethanol,” said Fred Katzenmeyer of Katz Brothers, a shop on Walnut Street that repairs vehicles as well as tractors and lawn equipment. Alongside parts for lawn mowers and other lawn-maintenance equipment, he’s been selling products that test and treat fuel in small engines when ethanol and gasoline separate in moist enough conditions — leaving fuel tanks and carburetor bodies on mowers and weed trimmers susceptible to corrosion due to typical, sparing usage.

“Most people don’t leave a car sitting a month or two months before they run it,” Katzenmeyer said. “That’s why they’re getting away with it on automobiles. Anyone who’s affected is anyone who leaves here ticked because they spent $60 to clean out their engine.”

“I couldn’t crank the thing when I put (ethanol-blended gas) in there,” said Joe Wooley, who was advised to use premium gas in his weed trimmer when E10 left him high and dry. “I put some 93 in there and haven’t had a problem since.”

In 2008, the Mississippi Legislature redefined allowable gasoline mixtures to include the grain alcohol. The new definitions were renewed by state lawmakers in 2010, though mixing percentages of ethanol remains completely optional for gas station operators.

Two Vicksburg gas stations — Port Mart on North Washington Street and BG Jr. on East Clay Street — have advertised in print their non-ethanol pumps to owners of lawn equipment, boats and all-terrain vehicles, stressing better performance.

“Customers want to have it,” said Richard Waring, vice president of Waring Enterprises, which operates the two locations. “A lot of equipment is not made for ethanol.”

Gray counted himself among regular visitors to the red-handled, pure-gas pumps. “I’m very thankful,” he said. “It may cost 20 cents more a gallon, but I’m thankful.”

Boat manufacturers, who joined automakers and outdoor power equipment makers in one of multiple lawsuits against the EPA after the October decision, also contend motors in boats — often laid up in the backyard between prime fishing seasons — can corrode with automotive-strength ethanol blends.

“It was about a 20 percent decrease in performance,” said Dane Mitchell, whose bass boat covered only 100 miles per tank with E10 versus 130 to 140 miles on pure gasoline.

Fuel treatments for boats are consistent sellers at Carruthers Marine on Washington Street, even with fairly new motors, said manager Joey Simmons.

“The older boat motors have more issues than the newer ones, but there’s still that release process with fuel systems,” Simmons said.

Ethanol’s fuel additive forerunner, methyl tertiary butyl ether, or MTBE, was found to contaminate groundwater and soil and has been phasing out since the federal government in 2006 stopped requiring refiners to use it. A year earlier, Congress mandated ethanol consumption by drivers increase up to 50 percent by 2012.

About 300 licenses to blend ethanol have been issued by the state since E10 began appearing at gas stations statewide, Mississippi Department of Agriculture and Commerce spokesman Andy Prosser said, adding the department takes frequent calls about what to do about equipment powered by 2- and 4-cycle engines. They advise the same as most owners’ manuals that come with small, motorized equipment.

“For small engines, we recommend in the wintertime that you run the fuel out of it,” Prosser said.

The ethanol industry estimates about six out of 10 cars on the road could use ethanol under the new standards. Decisions by the EPA on the safety of E15 were delayed multiple times as the agency and the Department of Energy tested it. Results indicate the higher blend was approved only for newer cars with more durable emissions systems.

Success of E15 will depend on how consumers accept it, and more studies are necessary to find out how more ethanol in gasoline could affect vehicles “designed and warranted” for the current 10 percent blend, according to a statement from the Alliance of Automobile Manufacturers after the EPA’s most recent decision. The group represents a dozen automakers, including Toyota and the U.S. “big three,” General Motors, Ford and Chrysler.

Production of cellulosic ethanol, made from switchgrass instead of corn, has picked up slightly with the startup of two demo plants in the Midwest, though it trails far behind the pace of corn-based ethanol production in the U.S., pegged at more than 7 billion gallons annually.

Loan guarantees totaling $405 million for three non-grain ethanol plants were announced by the Department of Agriculture a day before EPA’s ruling. The largest, at $250 million, went to Coskata Inc., which plans to turn woody biomass into ethanol at a facility in Greene County, Ala. Another, for $80 million, went to Enerkem Corp. for a plant in Pontotoc, which will use post-consumer municipal waste to make the additive. The third went to INEOS New Planet Energy for a cellulosic ethanol plant in Vero Beach, Fla.