Tank Vent - Stihl 034 Series User Manual

Erratic idling behavior, poor
acceleration:
– Idle setting too lean. Turn the low
speed screw counterclockwise
until the engine runs and
accelerates smoothly.
Exhaust smokes at idle speed:
– Idle setting too rich. Turn the low
speed screw clockwise until
engine speed drops.
– Then turn it back one quarter turn
from that position.
– Check that the engine
accelerates smoothly when the
throttle is opened.
034, 036, 036 QS
12.6

Tank Vent

Correct operation of the carburetor
is only possible if atmospheric
pressure and internal fuel tank
pressure are equal at all times. This
is ensured by the tank vent.
Important:
In the event of trouble with the
carburetor or the fuel supply
system, always check and clean the
tank vent.
– Remove the air filter -
On older tank housings (up to
serial number X 32 185 626)
remove the original type tank
vent (arrow) by pulling it upwards.
2
Take out the pan head screw (1)
and the grub screw (2).
When assembling the tank vent,
make sure the grub screw is fitted
squarely.
3
2
1
4
On machines from serial number
see 12.1
X 32 185 626, pull off the cap
(3) and filter (2) vertically.
Inspect previous valve (1), or new
valve (4), for damage and, if
necessary, replace as follows:
Pull the previous valve (1) out of
the tank housing from outside
and install it from outside.
In case of new valve (4), first
drain the fuel tank. Then pull the
valve out of the tank housing from
inside. Install new valve from
inside the fuel tank, and carefully
pull the stem from outside until
the valve is properly seated.
– Wash all parts in clean gasoline
and blow clear with compressed
air.
Reassemble in the reverse
sequence.
Note:
Overpressure may occur in the fuel
1
tank (e.g. due to heat build-up or
exposure to sunlight). Always open
the tank cap carefully so as to allow
any pressure build-up to release
slowly.
67