Husqvarna K1270 II Workshop Manual page 37

6.6.3 Needle valve
6.6.3.1 Indications of a needle valve leak
There are many symptoms of a needle valve with a leak.
A product that is used for short periods is usually not
easy to start when it is warm. Fuel leaks into the venturi
and gives too much fuel for the next warm start.
With a cold start, the fuel chamber above the needle
valve is dry. This is the situation especially when the
product has not been used for a long period. After trying
to start many times, new fuel has gone into the
carburetor and the product starts.
6.6.3.2 Test conditions
The best test result is from a carburetor that is drained,
but has some fuel left. Do not examine a fully dry
carburetor, or a carburetor that has not been used for a
long time.
6.6.3.3 To prepare the needle valve test
1. Connect a piece of hose to the fuel line.
2. Increase the pressure until fuel runs out through the
venturi.
Note: The maximum permitted pressure during the
test is 36 psi/2.5 bar.
If the needle valve does not open at 36 psi/2.5 bar, the
needle valve has locked. Blow through the hole for filter
compensation to open the needle valve.
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6.6.3.4 To do a test of the needle valve
1. Connect the pressure tester to the fuel line.
2. Increase the pressure to 14.5-36 psi/1-2.5 bar.
If the needle valve operates correctly, it lifts. The
pressure then decreases to approximately
14.5-7.2psi/1.0-0.5 bar and then decreases much
slower or stops. A pressure drop after 7.2 psi/0.5 bar
means there is a leak. The leak can be in the needle
valve, the pump unit (A) or the measurement
chamber (B). If there is a leak, first make sure that
the screws on the pump and the measurement
chambers covers are tightened. If the pump and
measurement chamber covers are tight, examine
the needle valve. Refer to
needle valve on page 38 .
A
6.6.3.5 To examine external leakage and the function of
the needle valve
1. Lower the carburetor into water.
2. Connect the pressure tester to the fuel line.
3. Increase the pressure to 7-14 psi/0.5-1 bar.
4. Examine if air comes out from the carburetor.
To examine and clean the
B
Repair and servicing - 37