Fuel Specifications; Fuel - Mercury MCM Series Important Information Manual

Fuel Specifications

Fuel

! CAUTION
Use of improper gasoline can damage the engine
seriously. Engine damage that results from use
of improper gasoline is considered misuse of the
engine and is not covered under MerCruiser War-
ranty.
USA and Canada
Fuel having a posted pump Octane Rating of 87 (R +
M) / 2 minimum. Premium gasoline [92 (R + M) / 2] is
also acceptable . DO NOT use leaded gasolines.
Outside USA and Canada
Fuel having a posted pump Octane Rating of 92 RON
minimum. Premium gasoline (98 RON) is also ac-
ceptable. If unleaded is not available, use a major
brand of leaded gasoline.
Gasolines containing alcohol, either methyl alcohol
(methanol) or ethyl alcohol (ethanol) may cause in-
creased:
Corrosion of metal parts.
Deterioration of elastomer and plastic parts.
Fuel permeation through flexible fuel lines.
Wear and damage of internal engine parts.
Starting and operating difficulties.
Some of these adverse effects are due to the tenden-
cy of gasolines containing alcohol to absorb moisture
from the air, resulting in a phase of water and alcohol
separating from the gasoline in the fuel tank.
The adverse effects of alcohol are more severe with
methyl alcohol (methanol) and are worse with in-
creasing alcohol content.
! WARNING
Fire and Explosion Hazard: Fuel leakage from
any part of the fuel system can be a fire and ex-
plosion hazard which can cause serious bodily
injury or death. Careful periodic inspection of the
entire fuel system is mandatory, particularly after
storage. All fuel system components including
fuel tanks (whether plastic, metal or fiberglass),
fuel lines, primer bulbs, fittings, fuel filters and
carburetors should be inspected for leakage,
softening, hardening, swelling or corrosion. Any
Index
1B-8 - MAINTENANCE
sign of leakage or deterioration requires replace-
ment 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 pres-
ence of alcohol is unknown, increased inspec-
tion frequency for leaks and abnormalities is re-
quired.
! WARNING
Avoid gasoline fire or explosion. Improper instal-
lation of brass fittings or plugs into fuel pump or
fuel filter base can crack casting and/or cause a
fuel leak.
IMPORTANT: When operating a MerCruiser en-
gine 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, alco-
hol-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, inter-
nal corrosion may take place during storage if al-
cohol has washed protective oil films from inter-
nal components.
GASOLINE / ALCOHOL BLENDS
Many new motor vehicle owner manuals are warning
about the potential damage from using gasoline con-
taining alcohol, especially METHANOL. They cite
possible fuel system damage and performance prob-
lems. These are just two of the hazards that may be
caused by alcohol. These same problems as well as
the additional safety risk of fire and explosion from
fuel system leaks apply to marine inboard engines.
METHANOL is more severe in its bad effect than is
ETHANOL. Alcohol is also more severe in older en-
gines since newer engines have materials which are
more resistant to alcohol.
EFFECTS OF GASOLINE / ALCOHOL BLENDS
ON MARINE ENGINES
Corrosion of metals may result from use of alco-
hol-gasoline blends. Portable or permanently in-
stalled fuel tanks of metal or fiberglass, fuel filters,
fuel lines and float bowls may be affected by alcohol
blended fuels. Many fiberglass fuel tanks are slowly
dissolved by alcohol, leading immediately to filter and
carburetor plugging and eventually to tank failure.
Fuels containing alcohol will absorb moisture from
the air. At first, this moisture will remain in solution,
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