Stihl MS 311 Manual

72 MS 311, MS 391
: Push the fuel hose (1)
1110 141 8600 onto the
nipple (2) 0000 855 9200.
: Push the fuel hose with nipple
onto the carburetor’s fuel
stub (arrow).
165RA336 TG
2
1
0001RA342 TG
– 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,
sealing cone of inlet needle is
damaged or inlet control lever is
sticking). Remove to clean,
b 12.6.2
2. Metering diaphragm or gasket
damaged, replace if necessary,
b 12.6.1
3. Pump diaphragm or gasket
damaged, replace if necessary,
b 1 2 . 6 . 3
– After completing the test, push
the ring (1) to the left to vent the
system and then pull the fuel
hose off the carburetor.
– Install the filter base, b 12.3
– Reassemble all other parts in the
reverse sequence.
1
2
0001RA346 TG
12.6 Servicing the Carburetor
12.6.1 Metering Diaphragm
– Troubleshooting, b 3.6
– Remove the carburetor, b 12.5
: Take out the screws (arrows).
– Remove the end cover (1).
If the gasket and diaphragm are
stuck to the carburetor, remove
them very carefully.
: Carefully separate the metering
diaphragm (1) and gasket (2).
The diaphragm material is
subjected to continuous alternating
stresses and eventually shows
signs of fatigue. i.e. the diaphragm
distorts and swells and has to be
replaced.
– Check the metering diaphragm
for signs of damage and wear.
Install a new gasket.
4903RA187 TG
1
0001RA348 TG
12

Stihl MS 311 Specifications

General

Oil tank capacity	0.348 L
Fuel tank capacity	0.6 L
Power source	Gasoline

Weight and Dimensions

Weight	6200 g