Stihl FS 311 Instruction Manual page 9

Sometimes also referred to as "fuel
geysering," fuel spraying is an expulsion
of fuel, vapors and fumes which can
occur in hot conditions, or when the
engine is hot, and the tank is opened
without allowing the power tool to cool
adequately. It is more likely to occur
when the fuel tank is half full or more.
Pressure is caused by fuel and heat and
can occur even if the engine has not
been running. When gasoline in the fuel
tank is heated (by ambient
temperatures, heat from the engine, or
other sources), vapor pressure will
increase inside the fuel tank.
Some blends of gasoline, particularly
those designed for use in winter, are
more volatile and may cause tanks to
pressurize more quickly or create
greater pressure. At higher altitudes,
fuel tank pressurization is more likely.
How to Avoid Fuel Spraying
Removing the fuel cap on a pressurized
tank can result in gasoline, vapors and
fumes being forcefully sprayed out from
the fuel tank in all directions. To reduce
the risk of burns, serious injuries or
property damage from fuel spraying:
Follow the fueling instructions in this
–
chapter.
Always assume your fuel tank is
–
pressurized.
Allow the power tool to cool before
–
removing the fuel cap.
FS 311
In hot environments, cooling will
–
take longer.
The engine is air cooled. When it is
–
shut off, cooling air is no longer
drawn across the cylinder and the
engine temperature will rise for
several minutes before starting to
cool.
After the power tool has cooled
appropriately, follow the safety
instructions in this chapter for removing
the cap.
Never remove the fuel filler cap by
turning it directly to the open position.
First check for residual pressure in the
tank by slowly turning the cap
approximately 1/2 turn counter-
clockwise. The cap should be held in
place by the threads while allowing
residual vapor/pressure to be relieved.
Once the fumes or vapor have been
relieved, turn the cap further until it can
be removed from the tank opening.
Use only good quality fuel that is
appropriate for the season (summer v.
winter blends). Some blends of
gasoline, particularly winter blends, are
more volatile and can contribute to fuel
spraying.
Removing the Threaded Fuel Filler Cap
WARNING
After allowing the power tool to cool,
remove the fuel filler cap slowly and
carefully to allow any remaining
pressure build-up in the tank to release:
While maintaining steady,
–
downward pressure, slowly turn the
cap approximately 1/2 turn counter-
clockwise.
If any significant venting occurs,
–
immediately re-seal the tank by
turning the cap clockwise to the
closed position. Allow the power
tool to cool further before
attempting to open the tank.
Turn the cap to the open position
–
only after the contents of the tank
are no longer under pressure.
Never remove the cap by turning it
–
directly to the open position. First
allow the power tool to cool
adequately and then release any
residual pressure by slowly turning it
approximately 1/2 turn counter-
clockwise.
Never attempt to remove the cap
–
while the engine is still hot or
running.
English
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