Ethanol Fuel Attacks Outboard Engines, Inboard Engines and Fuel Tanks
Blended fuels present new, and potentially costly, problems for gasoline engines.
Who wouldnít accept with open arms a renewable product that is produced right here in the United States, reduces our dependency on foreign oil, and reduces pollution? Youíve probably already heard of biodiesel, a fuel made from, among other things, soybeans and used deep-fryer oils. Similarly, ethanol or ethyl alcohol is made from various agricultural products such as sugar cane and corn. (Itís what moonshiners used to make in rural stills in the early part of the last century.) Here in the U.S., where huge quantities of corn are grown, this seems like a natural fit. When mixed with gasoline, usually at a 10-percent ratio, itís referred to as either E10 or gasohol. The resulting product, an oxygenate, allows fuel to burn more efficiently and thus produces less pollution.
The main impetus for using or switching to E10 stems from the problems that the previous pollution-reducing additive, MTBE (an acronym for a type of ether and known carcinogen), was causing when it leaked from underground storage tanks into ground water.
The switch to E10 created almost immediate noticeable effects in one of the largest recreational boating regions in the U.S., the Northeast and Long Island Sound. Initially, mixing fuel that contained MTBE and ethanol created a sludgy material that quickly clogged fuel filters, carburetors, and fuel injection systems. Anecdotal evidence suggests that fuel system repairs in this region increased noticeably during the 2005 boating season.
That problem paled in comparison, however, to the effect that E10 appears to be having on the luckless owners of gasoline-powered vessels equipped with fiberglass fuel tanks.
Fiberglass is acknowledged by many boatbuilders and professionals in the marine industry as the material to use for a "forever tank." It doesnít rust, corrode, or otherwise suffer like other materials. (It fades and needs wax, but thatís not an issue for fuel tanks.) Fiberglass fuel tanks are more expensive than other materials such as steel, aluminum, and plastic, and as a result, they often found their way into high-end power cruisers and sportfishing boats such as those made by Hatterass, Bertram, and Chris Craft in the í60s and í70s, along with some later-model small boats like Boston Whalers.
When used to store E10, these fiberglass tanks dissolve, literally. The alcohol, which is a solvent, begins to molecularly disassemble the fiberglass resin matrix. Eventually, the tank may become structurally unstable as it softens, and fuel may begin to leak. A number of cases have already been reported.
As if this isnít bad enough, the dissolved components, styrene and polyester, make their way along with the fuel to the engine. The result is a black, gooey substance that can be found beneath the carburetor and on valves and valve guides. This often leads to valve seizure, poor running, and eventually engine failure. In some cases, repairs are not economically feasible. Ethanol may also damage plastic and rubber components such as fuel lines and filters. Fuel hose that is alcohol-resistant, such as type A1, is usually so labeled.
If you suspect you have fuel in your tank that contains MTBE, try to use it up before refilling with new fuel that may contain ethanol. If you have fiberglass tanks, you will probably be facing the unpleasant task of replacing your fuel tanks with aluminum, upgraded fiberglass, polyethylene, or stainless steel (ABYC now approves stainless steel as long as itís 316L and at least .075 inches thick.)
The final nail in the E10 coffin is ethanolís affinity for water it absorbs it and holds it in suspension, to a point. In some cases, this may be desirable. Some water-absorbing "dry gas" products allow water to be suspended and then burned with the fuel. But too much water can present a problem. If the water content of the tank rises much above 0.5 percent thatís half a gallon in a 100-gallon tank the ethanolís water-supporting capacity will be overwhelmed. This is called phase separation. The ethanol/water mix will drop out of the fuel and sink to the bottom of the tank where your engine will suck it up. Engines donít run well, if at all, on this gelatinous mixture. Plus, the remaining fuel in the tank, now devoid of the ethanol, will be of a significantly lower octane rating, as low as 83, which will also lead to running problems.
E10 fuel is apparently less stable than ordinary gasoline, on the order of 60 to 90 days. So some experts are now suggesting, contrary to previously held wisdom, that tanks be stored empty rather than full. A tank full of E10 may spoil, and it will tend to absorb water through fuel vents, leading to more trouble for the tank and the engine. Fuel stabilizers will help and should be used even for short-term fuel storage; however, seasonal lay-up is probably too long to rely on additives.
Evidence indicates that 40 percent of all service stations will be selling E10 by the time you read this, and that number is likely to grow. Whatís next? E20, and some locations are offering E85.