FS 91, FS 91 R
English
6
It may be carried only in a horizontal 
position. Grip the shaft in a manner that 
the machine is balanced horizontally. 
Keep the hot muffler away from your 
body and the cutting attachment behind 
you.
WARNING
Always shut off the engine and make 
sure the cutting attachment has stopped 
before putting a trimmer / brushcutter 
down. When transporting it in a vehicle, 
properly secure it to prevent turnover, 
fuel spillage and damage to the unit. 
STIHL recommends that you keep metal 
blades covered with the transport guard 
(optional accessory).
Fuel
Your STIHL power tool uses an oil- 
gasoline mixture for fuel (see the "Fuel" 
chapter in this instruction manual).
WARNING
Fueling Instructions
WARNING
To reduce the risk of fire and serious 
personal injury, always place the power 
tool on the ground before attempting to 
fuel the machine.
WARNING
Pick a Safe Location
To reduce the risk of fire and explosion, 
fuel your power tool in a well-ventillated 
area, outdoors away from flames, pilot 
lights, heaters, electric motors, and 
other sources of ignition.  Vapors can be 
ignited by a spark or flame many feet 
away. Select bare ground for fueling and 
move at least 10 feet (3 m) from the 
fueling spot before starting the engine.  
Wipe off any spilled fuel before starting 
your power tool. Take care not to get fuel 
on your clothing. If this happens, change 
your clothing immediately.
Allow the Power Tool to Cool Before 
Removing the Fuel Cap
WARNING
Gasoline vapor pressure may build up 
inside the fuel tank. The amount of 
pressure depends on a number of 
factors such as the fuel used, altitude 
and temperature. To reduce the risk of 
burns and other personal injury from 
escaping gas, vapor and fumes, always 
shut off the engine and allow it to cool 
before removing the fuel cap.
The engine is air cooled. When it is shut 
off, cooling air is no longer drawn across 
the cylinder and engine temperatures 
will rise for several minutes before 
starting to cool. In hot environments, 
cooling will take longer. To reduce the 
risk of burns and other personal injury 
from escaping gas, vapor and fumes, 
allow the power tool to cool. If you need 
to refuel before completing a job, turn off 
the machine and allow the engine to cool 
before opening the fuel tank.
Fuel Spraying or “Geysering”
WARNING
Removing the cap on a pressurized fuel 
tank can result in gasoline, vapors and 
fumes being forcefully sprayed out from 
the fuel tank in all directions. The 
escaping gasoline, vapors or fumes can 
cause serious personal injury, including 
fire and burn injury, or property damage.
Gasoline is an extremely 
flammable fuel. If spilled 
and ignited by a spark or 
other ignition source, it 
can cause fire and seri-
ous burn injury or 
property damage. Use 
extreme caution when 
handling gasoline or fuel 
mix. Do not smoke or 
bring any fire or flame 
near the fuel or the power 
tool. Note that combus-
tible fuel vapor may 
escape from the fuel 
system.