Leakage Testing; Carburetor Repair; Air Flap - Stihl MS 441 Manual

14.3.1 Leakage testing

In the case of problems with the
carburetor or fuel supply system,
also check and clean the tank vent,
b 14.7.
The carburetor can be tested for
leaks with the pump
0000 850 1300.
– Remove carburetor, b 14.3.
2 1
: Push fuel line (1) 1110 141 8600
onto nipple (2) 0000 855 9200.
: Push fuel line with nipple onto
fuel connection (arrow).
100
2
1
– Connect pressure hose of pump
0000 850 1300 to nipple.
: Slide ring (1) to the right and
pump air into the carburetor until
the pressure gauge (2) shows
a reading of approx. 0.8 bar
(80 kPa).
If this pressure remains constant,
the carburetor is airtight. If it drops,
this may be due to three causes:
1. Inlet needle valve is not sealing
(impurities in valve seat or
sealing cone of inlet needle is
damaged or inlet control lever
sticking). Remove to clean,
b 14.4.3.
2. Metering diaphragm or gasket is
damaged, replace if necessary,
b 14.4.2.
3. Pump diaphragm or gasket is
damaged, replace if necessary,
b 14.4.5.
– After completing the test, slide
ring (1) to the left and vent the
system, then disconnect fuel line
from elbow connector of
carburetor.
– Install carburetor, b 14.3.
– Tightening torques, b 3.5.
– Reassemble all other parts in the
reverse sequence.
14.4

Carburetor repair

14.4.1 Air flap

3
1
The air flap must not be removed,
nor may any changes be made in
the control system.
– Troubleshooting chart, b 4.6.
The screws (arrows + 1, 2) are
bonded into place and must not be
loosened or removed.
Screws (1+2) and adjusting
screw (3) must not be adjusted,
otherwise the manufacturer's
setting will no longer be correct and
operation may be impaired.
Check air flap
: In idle position, the air flap
(arrow) must make contact with
the housing all round and seal the
air duct.
MS 441, MS 441 C
2