Tank Vent; Check - Stihl MS 441 Manual

14.7

Tank vent

14.7.1 Check

Always check and clean the tank
vent in the event of trouble with the
carburetor or fuel supply system,
replace if necessary. Check function
by testing the fuel tank under
vacuum or at gauge pressure via
the fuel hose.
– Open fuel filler cap and drain fuel
tank.
Collect fuel in a clean container and
dispose of it in accordance with
environmental regulations.
– Close fuel filler cap.
– Remove carburetor, b 14.3,
before checking function via fuel
hose.
Work through the following steps
and repeat the test if a leak is found.
– Remove carburetor housing,
b 14.6.2.
1
: Pull out elbow connector (1).
120
1
: Push nipple (1)
0000 855 9200 into flange
(arrow) of intake hose.
1
Vacuum test
: Slide ring (1) to the left and
connect pump (2) 0000 850 1300
to nipple (arrow).
Build up vacuum in fuel tank.
Equalization of pressure takes
place via the tank vent. A vacuum
must not build up in the tank.
– Clean area around the tank vent.
– Replace tank or tank vent if
necessary, b 14.7 or b 14.8.4.
1
Pressure test
: Slide ring (1) to the right and
connect pump (2) 0000 850 1300
to nipple (arrow). Build up
pressure in fuel tank.
– Actuate pump until pressure
gauge shows a reading of
0.5 bar. If this pressure is
maintained for at least
20 seconds, the tank and tank
2 vent are airtight. If the pressure
drops, the leak must be located
and the faulty part replaced.
– Reassemble in the reverse
sequence.
2
MS 441, MS 441 C