Replacing The Air Filter; Cleaning The Spark Plug - Stihl Fs 251 R Notice D'emploi

English
Condition
The engine idles
erratically.
The engine stops
while idling.
The cutting attach‐
ment rotates when
the engine is idling.
The engine does not
reach maximum
speed.
The fuel tank is not
completely emptied.
21.2

Replacing the Air Filter

Dirty air filters reduce engine power, increase
fuel consumption and make starting more diffi‐
cult.
If there is a noticeable loss of engine power:
► Shut off the engine,
► Allow the trimmer / brushcutter to cool down.
► Turn the choke lever to
3
2
1
► Loosen the screws (1).
► Remove the air filter cover (2).
► Clean the area around the air filter with a
damp cloth or a soft brush.
► Remove the air filter element (3).
► Fit the new filter in the filter housing.
► Fit the filter cover.
► Insert the screws (1) and tighten them.
34
Possible Cause
The carburetor is too hot.
The carburetor is iced up.
The carburetor is iced up.
The carburetor is iced up.
The throttle cable is not set correctly.
The idle speed is not set correctly.
The throttle cable is not set correctly.
The pick-up body / filter inside the fuel
tank is not in place.
12.1.
position.
Remedy
► Cool down the trimmer / brushcutter.
► Before starting the engine. Press the
manual fuel pump bulb at least ten
times – even if the bulb is filled with
fuel.
► Allow the engine to warm up gradu‐
ally to a temperature of about 50 °F
(10 °C).
► Allow the engine to warm up gradu‐
ally to a temperature of about 50 °F
(10 °C).
► Allow the engine to warm up gradu‐
ally to a temperature of about 50 °F
(10 °C).
► Adjusting the throttle cable,
► Adjust the trimmer's / brushcutter's
idle speed,
► Adjusting the throttle cable,
► Have the pick-up body / filter
checked by an authorized STIHL
servicing dealer.
21.3

Cleaning the Spark Plug

WARNING
■ To reduce the risk of fire and burn injury, use
only spark plugs authorized by STIHL. Always
press the spark plug boot snugly onto the
spark plug terminal.
1
WARNING
■ Do not use a spark plug with a detachable
SAE adapter terminal (1). Arcing may occur
that could ignite combustible fumes and cause
a fire. This can result in serious injuries or
damage to property. Only use resistor type
spark plugs with solid, non-threaded termi‐
nals (2).
Using the wrong fuel mix (too much engine oil in
the gasoline), a dirty air filter, and unfavorable
running conditions (running for extended periods
21 Troubleshooting Guide
21.5.
21.4.
21.5.
2
0458-853-8201-A