Coping with ethanol

Posted on 30 June 2009 Written by Chris Landry

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Ethanol has an affinity for water and will absorb it until the amount of water in the solution reaches a point where the alcohol drops out of, or "separates," from the fuel and collects in the bottom of the tank - that's phase separation.

There, the mixture of alcohol and water promotes the growth of bacteria, which can lead to damaging sludge. Also, the alcohol/water mix, if allowed to build up sufficiently, can actually be picked up and delivered through the fuel system, also causing serious problems.

Here's some advice for dealing with ethanol fuel formulations in the marine environment.

More on ethanol problems
• Everyone Hates Ethanol
- Wall Street Journal

• The Clean Energy Scam
- Time magazine

• The Ethanol Scam
- Rolling Stone

There are at least two schools of thought when it comes to how full the tank should be during offseason layup. Some engine manufacturers recommend treating the fuel and storing the tank 7/8 full, leaving some room for expansion. This helps reduce condensation and phase separation. In contrast, some technicians recommend draining as much fuel out of the tank as possible before layup. Since ethanol's shelf life is only 90 days, these technicians would rather deal with a smaller amount of old E10 than a full tank when it's time to launch the boat again.

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