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STIHL 029, 039
60
11.4
Servicing the
Carburetor
11.3
Leakage Testing the
Carburetor
Fastening screw on fuel
pump end cover
Pressure testing carburetor with
carburetor/crankcase
tester 1106 850 2905
Zama and Walbro carburetors of
almost identical construction are
installed in these machines. The
servicing procedures for the Zama
carburetor are described below.
Differences in individual parts are
described separately.
It is advisable to check the service-
ability of the fuel pump whenever the
carburetor is removed for repair.
- Remove the carburetor –
- Unscrew the fuel pump end
cover and take it off.
- Close the vent screw on the rubber
bulb and pump air into the carburetor
until the pressure gauge shows a
reading of approx. 0.4 bar (5.8 psi).
If this pressure remains constant, the
carburetor is airtight. However, if it
drops, there are two 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).
2. The metering diaphragm is
damaged.
In either case the carburetor must
be removed and serviced.
The carburetor can be tested for
leaks with the carburetor and
crankcase tester.
- Remove the carburetor, - see 11.2.
- Connect tester's pressure hose to
elbow connector on side of car-
buretor. Note that a separate nipple
and a length of fuel line are required
to make this connection.
Top:
Nipple 0000 855 9200
fitted in fuel line
1110 141 8600
Bottom:
Fuel line on elbow
connector