Servicing The Carburetor; Metering Diaphragm - Stihl MS 290 Manual

3
: Push the nipple into the pressure
hose of tester 1106 850 2905.
: Close the vent screw (1) on the
rubber bulb (2) and pump air into
the carburetor until the pressure
gauge (3) shows a reading of
approx. 0.8 bar (80 kPa).
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). Remove to clean,
b 11.3.2
2. Metering diaphragm damaged,
replace if necessary, b 11.3.1
– After completing the test, open
the vent screw (1) and pull the
fuel line off the carburetor.
– Push the fuel hose onto the
elbow connector.
– Install the carburetor, b 11.2.1
Reassemble all other parts in the
reverse sequence.
MS 290, MS 310, MS 390
11.3

Servicing the Carburetor

11.3.1 Metering Diaphragm

2
1
– Remove the carburetor,
b 11.2.1
Carburetor without limiter caps
: Take out the screws (arrows).
: Remove the end cover (1).
Carburetor with limiter caps
: Take out the screws (arrows).
: Remove the end cover (1).
1
: Remove the metering diaphragm
and gasket (arrow) from the
carburetor body or end cover.
If the gasket and diaphragm are
stuck to the carburetor, remove
them very carefully.
1
: Carefully separate the diaphragm
and gasket.
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