Mercury MerCruiser 4.3 TKS, User Manual

Page: 48 / 122

Section 4 - Specifications
Page 40 90-899883179 OCTOBER 2007
Fuel Requirements
IMPORTANT: Use of improper gasoline can damage your engine. Engine damage
resulting from the use of improper gasoline is considered misuse of the engine, and
damage caused thereby will not be covered under the limited warranty.
Fuel Ratings
Mercury MerCruiser engines will operate satisfactorily when using a major brand of
unleaded gasoline meeting the following specifications:
USA and Canada—
having a posted pump Octane Rating of 87 (R+M)/2 minimum.
Premium gasoline [92 (R+M)/2 Octane] is also acceptable. Do not use leaded gasoline.
Outside USA and Canada—
having a posted pump Octane Rating of 90 RON minimum.
Premium gasoline (98 RON) is also acceptable. If unleaded gasoline is not available, use
a major brand of leaded gasoline.
Using Reformulated (Oxygenated) Gasolines (USA Only)
This type of gasoline is required in certain areas of the USA. The 2 types of oxygenates
used in these fuels is Alcohol (Ethanol) or Ether (MTBE or ETBE). If Ethanol is the
oxygenate that is used in the gasoline in your area, refer to Gasolines Containing Alcohol.
These Reformulated Gasolines are acceptable for use in your Mercury MerCruiser engine.
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 boat's
fuel system components (fuel tanks, fuel lines, and fittings). Be aware that gasolines
containing alcohol may increase:
• Corrosion of metal parts
• Deterioration of rubber or plastic parts
• Fuel permeation through rubber fuel lines
• Difficulty starting and operating the engine
!
WARNING
Fuel leakage is a fire or explosion hazard, which can cause serious injury or death.
Periodically inspect all fuel system components for leaks, softening, hardening, swelling,
or corrosion, particularly after storage. Any sign of leakage or deterioration requires
replacement before further engine operation.
Because of possible adverse effects of alcohol in gasoline, we recommend only
alcohol‑free gasoline when possible. If the only fuel available contains alcohol or if you do
not know whether the fuel contains alcohol, inspect for leaks and abnormalities more
frequently.