How boaters use special fuel filters
and fuel additives with E-10 gas for problem free
running
By now you know that Ethanol-laced gasoline is notorious for causing
big problems with outboard motors, stern drives and inboard engines. Whether
or not it should ever put to sea is a moot point. That’s what’s on the fuel
docks whether we like it or not. But the fact of the matter is that boat
owners need not suffer. In fact, millions of boaters burn E-10 without
problems. Here’s how to make this biofuel work for you
E-10 is a U.S.
government-mandated blend of 10 percent alcohol and 90 percent gasoline.
While E85 (sometimes also called E-15) is a blend of 15 percent alcohol and
85 percent gasoline. We won’t delve into the politics here. Suffice it to say
that on the highway this renewable fuel works well enough. But the problem on
a boat is the simple fact that ethanol, or grain alcohol, is both a solvent
and hygroscopic.
As a solvent, it readily
dissolves gum, varnish and rust that’s built up on the bottom of the fuel
tank. The engine’s fuel pump sucks it out of the tank and deposits it in the
fuel filter. Soon the filter is plugged and the engine starves for fuel.
That’s why it’s all too common to go through multiple fuel filter changes
until the day when the fuel system has finally been scrubbed squeaky clean.
The obvious solution is to change fuel filters often and have plenty of
spares on board.
What’s more, ethanol leeches resin and plasticizers from fiberglass, plastic
and rubber. So the inside walls of fiberglass fuel tanks, like those
installed in Bertram, Chris Craft and Hatteras boats built back in the 60’s
and 70’s go soft. The resin turns into jelly. The jelly flows downstream to
the filters with predictable results. Some of the dissolved resin flows past
the fuel filters deposits itself as a black sludge on the intake valve stems
causing them to stick in their guides.
Also, fuel injectors and carburetor
jets clog. It isn’t pretty. In time the softened tanks begin to weep fuel
into the bilge. That erodes mileage and is a fire and explosion hazard.
Vinylester resins are impervious to ethanol, though epoxy and polyester
resins are not.
Another tantalizing
tidbit of information is that newer boats without fiberglass tanks and
without years worth of gum build-up tend to be more trouble free when fuel
is filtered through a 10-micron element, as opposed to sister ships with the
more typical 30-micron filtration. Both Yamaha Marine and Racor offer
10 micron fuel filters with specific model appropriate for boats as small as
dingy tenders up to big block V-8s.
Racor's Aquabloc
filter media forces water to the
bottom of the drain bowl where it can be drained off. Racor claims nearly 100
percent removal of water and solid contaminants.
On larger craft we find
the more expensive three-stage filter system The primary stage literally
centrifuges the gasoline, causing large particulate matter and water droplets
to fall down into the sediment bowl. The second stage coalescing ring causes
remaining water to form into droplets and also fall into the sediment bowl.
All at the same time, dry fuel flows to the engine.
Remember in the beginning when we said ethanol is hygroscopic? That means it
pulls water out of the atmosphere. Alcohol loves water. The higher the
humidity, the greater the volume of water drawn into the fuel. So how much
water does gas need to absorb before it becomes a problem?
When just four teaspoons
of water per gallon (0.5%) contaminate the gasoline, the solution separates
into two distinct layers: Gasoline floats on the top and water saturated
alcohol sinks to the bottom.
Experts assert that in
70 percent humidity it only takes about three months to reach phase
separation. Though you could have problems sooner, which usually happens as
the result of a contaminated fuel supply. Know that the hottest sparkplug in
the world can’t ignite water. So naturally it follows, the engine sputters,
stalls, and eventually dies. There is a very simple solution: Plumb a
fuel/water separator in the fuel delivery line. More about that idea later on
in this story.
So how can you be sure gasoline is water-contained and not some other malady?
Again, there’s a simple answer. E-10 gasoline contaminated by water turns
white. The emulsion readily passes through filters. But when it hits .5
percent water, and phase separation occurs, the layer of gasoline reverts to
clear and bright, but is octane compromised.
At the refinery adding ethanol to base gasoline raised its octane by a couple
of numbers, say from 87 to 89. So naturally it follows, subtracting alcohol
(and water) from the blend lowers the octane to its original rating.
As a result horsepower fades, acceleration weakens and mileage worsens. Even
without phase separation E-10 delivers lower mileage per gallon (about 1.5
percent) for the simple reason that ten percent of the blend is ethanol, with
inherently fewer inherent BTUs than gasoline. BTUs burned equal work done.
There’s yet another
problem with E-10. Its shelf life runs from about six weeks to 90 days
before it begins to decompose. That means that even in a perfect water world
where there is no water contamination. the solution it’s wise to stabilize
fuel with an E-10 specific stabilizer. Three good brands worthy of
consideration are Marine Formula Sta-Bil specially formulated for E10,
Starbrite’s StarTron and PRI-G. Keep in mind these additives help to prevent
phase separation, but once it has occurred you are on your own.
The first line of defense is prevention, minimize the volume of water going
into your tanks at the fuel dock. When topping off the tanks, scrupulously
pre-filter every gallon pumped. It is a wise man who invests in a funnel that
incorporates a water separator.
The Racor Filter Funnel
is a heavy-duty fast flow filter in a funnel that separates free water
and contaminates down to .005 of an inch from gasoline, diesel, heating
oil, and kerosene. Free water collects in the sump.
The multi-stage Baja
Fuel Filter features a series of
mesh screens, coarse and fine, that
stop particulate matter and water at the point of entry. There are three
stages of filtration. The first coarse mesh traps sand and grit. Next the
fine mesh removes, well, finger grain matter. The third and final stage is a
specially treated mesh that removes all remaining debris and traps any water.
If you see lots of water in the filter after topping off, it's time to try a
new fuel dock with cleaner product.
©
Copyright 2009 by Tim Banse
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STA-BIL is a
venerable fuel stabilizer renowned for keeping gasoline from turning sour.
It is Americas #1 selling fuel additive brand. The new Marine Formula
STA-BIL, specifically formulated for ethanol fuel, boasts four times the
fuel system cleaner of 
