MAINTENANCE
SERVICE MANUAL NUMBER 25
90-861328--1 NOVEMBER 1999
Page 1B-9
CA618
GASOLINES CONTAINING ALCOHOL
If the gasoline in your area contains either “methanol” (methyl alcohol) or “ethanol” (ethyl
alcohol), you should be aware of certain adverse effects that can occur. These adverse
effects are more severe with “methanol.” Increasing the percentage of alcohol in the fuel can
also worsen these adverse effects.
Some of these adverse effects are caused because the alcohol in the gasoline can absorb
moisture from the air, resulting in a separation of the water/alcohol from the gasoline in the
fuel tank.
The fuel system components on your Mercury MerCruiser engine will withstand up to 10%
alcohol content in the gasoline. We do not know what percentage your boat’s fuel system
will withstand. Contact your boat manufacturer for specific recommendations on the boats
fuel system components (fuel tanks, fuel lines and fittings). Be aware that gasolines
containing alcohol may cause increased:
•
Corrosion of metal parts.
•
Deterioration of rubber or plastic parts.
•
Fuel permeation through rubber fuel lines.
•
Starting and operating difficulties.
WARNING
FIRE AND EXPLOSION HAZARD: Fuel leakage from any part of fuel system can be
a fire and explosion hazard which can cause serious bodily injury or death. Careful
periodic inspection of entire fuel system is mandatory, particularly after storage. All
fuel components including fuel tanks, whether plastic metal or fiberglass, fuel
lines, fittings, fuel filters and carburetors/fuel injection components should be in-
spected for leakage, softening, hardening, swelling or corrosion. Any sign of leak-
age or deterioration requires replacement before further engine operation.
Because of possible adverse effects of alcohol in gasoline, it is recommended that only alco-
hol-free gasoline be used where possible. If only fuel containing alcohol is available, or if
the presence of alcohol is unknown, increased inspection frequency for leaks and abnorma-
lities is required.
IMPORTANT: When operating a Mercury MerCruiser engine on gasoline containing
alcohol, storage of gasoline in the fuel tank for long periods should be avoided. Long
periods of storage, common to boats, create unique problems. In cars alcohol-blend
fuels normally are consumed before they can absorb enough moisture to cause
trouble, but boats often sit idle long enough for phase separation to take place. In
addition, internal corrosion may take place during storage if alcohol has washed pro-
tective oil films from internal components.
