Handling Ethanol in Older Marine Engines

The Boat US experts said in the 1980s new hoses were invented to handle "gasohol," as ethanol fuel was called. The hoses were invented because ethanol-laced fuel eats away rubber and plastic seals, standard fare for older marine motors. Since the invention of stronger, new compound hoses, that problem mostly has disappeared -- but not entirely because hoses don't last forever and need periodic maintenance checks. The experts recommend any fuel hoses more than 10 years old be replaced. A way to test a hose's strength is to wipe a clean rag along a hose, and if you smell gasoline on the rag, replace it.

As for carburetors and O-rings on older engines, with age they become hard and brittle after E-10 is run through them, with little bits and pieces breaking off causing clogs, misfires and even engine failure. Before 1990 carburetors were made from metal that wouldn't stand up to ethanol, which meant corrosion that caused small fuel holes to clog and tough-to-start engines and poor performance. Older carburetors also were made to handle just one type of fuel (pure octane). However, ethanol has more oxygen and affects the air/fuel ratio, causing engines to run leaner and hotter.

A good idea with older marine engines is to run gasoline with no E10 in it. If finding pure gasoline isn't an option, some mechanics, the experts said, may be able to recalibrate an older carburetor so it'll handle E10.As mentioned previously, it's a good idea to keep water out of fuel tanks and is imperative if using E10 because it can separate fuel into two solutions (water, fuel) in a tank (it's known as "phase separation"). This separation happens a lot in older motors that already may have water in the tank's bottom.