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Ethanol and Non-Ethanol Fuel: Some Facts, Some Fiction

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On: Fri, Feb 13, 2015 at 11:17AM | By: Captain Ron Kowalyk

I’ll hear about this skeed but I’m used to it. There are two or three or four schools of thought about the effects of ethanol on the operation of outboard motors. But one thing we can all agree on is that water in fuel is not good!

How does the H2O get into the fuel? Some old gas station tanks may leach in ground water, some old above ground tanks at lonely old marinas may build up moisture under very humid conditions and, worse yet, some unscrupulous stations and suppliers may “ water down” their fuel. The latter is very rare these days but I experienced the scenario once on a trip in Canada about a hundred years ago, up near Dugan’s, way up by Hudson Bay.

The newer four-stroke engines are not as vulnerable to the effects of burning ethanol fuel. Well, that’s generally true if you run your boat frequently and don’t store it months on end. Ethanol alone doesn’t have a detrimental effect on modern, newer four-strokes; even a two-stroke will run pretty well on fresh, clean, pure ethanol fuel of 10% ethanol. The problem is exacerbated when fuel is left in half-full tanks for a long period; this allows condensation to occur, in turn depositing water into your fuel. So don’t let your fuel age and mellow out, it’s not Scotch.

We get lots of “Snowbirds” here in Southwest Florida and they’re all expert boaters, “up north we put fuel stabilizer in our fuel and store our boats for six months over winter”, NOT! Come winter down here, between the dead batteries, gummy varnish-lined fuel tanks, and plenty of condensations rich fuel, they keep the shade tree mechanics real busy.

Don’t save that twenty bucks worth of fuel. In the old days guys would take off their fuel lines and carefully run the fuel outta their carburetors with the ear muffs on and siphon the fuel out into their boat tanks and use it in trucks or lawn mowers, maybe even have a nice beer and gas-fueled bonfire, and who knows what else. In a word, if you’ve got a small above-deck fuel tank, empty it. If you’ve got an under the deck tank, siphon it for long term storage. A system of fuel polishing for hire is available if you’ve got a monster boat with huge tanks. These companies will draw off your fuel, remove water and sediments, and help clean the fuel tank proper. Just a note: almost all modern engines are four-strokes or have VRO, variable ration oiling systems, so the fuel won’t contain oil and hurt any four-stroke engine.

A primary element to any fuel delivery system should be a quality inline water separator. Yamaha make some extra fine 10 micron filters, very effective. Some high-end water separators have a relief valve and clear plastic inspection cup on the bottom of the separator. The clear cup is very handy for a cursory inspection of fuel quality. If you periodically remove or, better yet, replace your water spectator, try pouring the contents into a clear plastic container and allow it to sit for a few minutes. Then inspect the fuel for water settling out on the bottom of the container; also check if there are any voyagers floating or settling out of the fuel. If you see any solid sediment, check your inline fuel filter at the engine.

Finally—we could go on and on—it was for a time illegal to sell non-ethanol fuel here in Florida at public service stations; that has changed. So if you’re happier and want to spend a few extra bucks, you can find non-ethanol fuel in most of Florida now. The gas additives, old timey “Dry Gas” that supposedly absorb water in ethanol fuel, are not necessary in four-stroke engines but might be somewhat useful in older two-stroke engines.

“Cool, Dry Runnings, Podnas”

PS: Keep your fuel clean and your shrimp frozen or alive or stinky and on the hook, circle hook that is!

Cappy Ron Kowalyk


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