Leakage Test; Servicing The Carburetor; Metering Diaphragm - Stihl MS 171 Manual

14.3.1 Leakage Test

In the case of problems with the
carburetor or fuel supply system,
also check and clean or replace the
tank vent, b 14.8
The carburetor can be tested for
leaks with the pump 0000 850 1300.
– Remove the carburetor, b 14.3
2 1
: Push the fuel line (1)
1110 141 8600 onto the
nipple (2) 0000 855 9200.
: Push the fuel line with nipple onto
the carburetor's fuel stub (arrow).
74
All manuals and user guides at all-guides.com
2
1
– Push the pressure hose of pump
0000 850 1300 onto the nipple.
: Push the ring (1) to the right and
pump air into the carburetor until
the pressure gauge (2) indicates
a pressure of about 0.8 bar
(80 kPa).
If this pressure remains constant,
the carburetor is airtight. However, if
it drops, there are three possible
causes:
1. The inlet needle is not sealing
(foreign matter in valve seat or
sealing cone of inlet needle is
damaged or inlet control lever
sticking), Remove to clean,
b 14.4.2
2. Metering diaphragm or gasket
damaged, replace if necessary,
b 14.4.1
3. Pump diaphragm or gasket
damaged, replace if necessary,
b 14.4.5
– After completing the test, push
the ring (1) to the left to vent the
system and then pull the fuel line
off the carburetor.
– Install the carburetor, b 14.3
– Reassemble all other parts in the
reverse sequence.
– Tightening torques, b 3.5
14.4

Servicing the Carburetor

14.4.1 Metering Diaphragm

– Troubleshooting,
– Remove the carburetor, b 14.3
: Take out the screws (arrows).
: Remove the end cover (1).
If the gasket and diaphragm are
stuck to the carburetor, remove
them very carefully..
MS 171, MS 181, MS 211
1