Westerbeke 3.5 MCGA 60 Hz Operator's Manual page 3

Operator Manual for Marine Gasoline Generators
WARNING: Gasoline with an ETHANOL content
rating higher than 10% (E-10) is not allowed and
may void warranty. Read the precautions below
from E-10 Service Bulletin #251 issued by
Westerbeke Corporation.
Since 1990, the U.S. government has mandated the use of oxygenated
fuels to reduce carbon emissions into the atmosphere. Congress had
previously mandated the use of MTBE (methyl tertiary butyl ether) as this
oxygenate. This legislation expired in May 2006 because MTBE is a known
carcinogen and is also a ground water contaminant. Since then, in new
energy legislation, Congress mandated the use of ethanol as the
oxygenate. Ethanol, an alcohol-based fuel produced from corn is more
environmentally friendly.
About E-10
E-10 is a blend of 10% ethanol and 90% gasoline and is the mixture now
offered at most fuel stations. The use of E-10 in your car should have no
real effect on its operation. The use of E-10 in the marine marketplace,
however, will cause us to take some precautions.
Ethanol, being an alcohol-based product, is quite different from MTBE
which is an ether-based product. Ethanol is sort of a double-edged sword
when it comes to its ability to mix with water. E-10 can hold up to four
teaspoons of water per gallon but can hold only 0.15 teaspoons of water
per gallon when in solution. This is good, as it will allow your engine to
burn water that finds its way into your fuel tank up to this 4-teaspoon per
gallon limit. The problem comes when one gets beyond this limit.
As was the case with MTBE fuel, E-10 will also phase separate when it gets
beyond the saturation point. Phase separation occurs when the gasoline
and water are separated and the gasoline floats on top of the water. With
MTBE, one could simply pump the water out from under the fuel or let
the filters remove it and burn the gasoline left behind. MTBE reacts quite
differently with water than does ethanol. For this reason, the two fuel
blends should not be mixed when transitioning from MTBE to E-10.
(Note: The original bulletin was written in 2006. In 2018 and future years, mixing with
MTBE is no longer a primary concern since it is no longer available.)
Ethanol is a solvent and tends to clean any dirt or contaminants on
contact. For the consumer, this means that any dirt currently in the fuel
system will be mixed into solution and scrubbed out by the fuel filters.
This results in the need for the consumer to change fuel filters frequently.
The shelf life of E-10 is only 60-90 days. It will start to break down over
time and leave deposits in the fuel system. E-10 will also lose its volatility
very quickly. We recommend using a NON-ALCOHOL based fuel
stabilizer in your fuel all the time. The reason we are recommending a
non-alcohol-based stabilizer is to avoid adding even more alcohol to the
fuel. There are several good petroleum-based products on the market.
Another characteristic of E-10 is its ability to absorb water directly from
the atmosphere through the open vent system of your boat tank. In just
100 days at 70% humidity, E-10 can absorb enough water to reach its
phase separation point. To avoid this from occurring, use up the fuel as
quickly as you can. Try to plan on turning the fuel over as quickly as
possible by running the tank low before any extended periods of non-
use. Then fill up just before the next trip out. Avoid having E-10 fuel sit
unused in the tank for an extended period.
E-10 Precautions
▪ Do not mix MTBE fuel with E-10 fuel.
▪ Keep water out of your fuel tank.
▪ Run a non-alcohol-based fuel stabilizer additive at all times.
▪ The more you use your boat the less likely you are to have problems.
Don't leave large loads of fuel in the boat for lengthy periods of time.
▪ There are approximately 5 to 8 percent fewer BTUs in E-10 (less
power per gallon).
▪ Have a good water-separating fuel filter installed if you don't already
have one.
▪ Keep several spare filters on board. You should also have a kit in a
sealable bucket that will seal up old filters and gas for safety and the
correct tools to change your filter. E-10 fuel will clean your fuel system
and consequently will often clog filters after changing.
▪ Be aware of potential points of water intrusion into fuel tanks. Check
deck fill cap O-rings and fuel vents.
▪ Ask your fuel supply source or marina about the ethanol content of
their fuel.
▪ Check and, if necessary, replace rubber fuel lines.
▪ Check and clean carburetors on older models.
Damage caused by contamination from water, foreign particles,
sludge, or gums entering or forming in the engine or fuel system is
not covered by the Westerbeke Corporation limited warranty.
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