Husqvarna K770 SmartGuard Workshop Manual page 32

6.5.3 To examine the fuel system for leakages
1. Connect the adapter to a pressure test tool. Refer to
Servicing tools overview on page 11 .
2. Increase the pressure to approximately 7 psi/0.5 bar.
If the pressure is constant, the fuel system has no
leakage. If the pressure drops, go to the next step.
3. To make sure that the fuel hose does not cause the
leakage, remove the carburetor unit. Seal the fuel
hose by the carburetor and do the pressure test
again. If the fuel hose is not damaged, the
carburetor must be examined.
6.5.4 To remove and install the fuel hose
• Push the fuel hose down in the tank. At the same
time, pull it out from the hole for the fuel tank cap.
32 - Repair and servicing
6.5.5 Function of the tank venting
The fuel tank has a check valve that lets air enter the
tank, but prevents fuel leakage. The filter lets air through
slowly.
6.5.6 Tank air flow fault indication
If the tank air flow is blocked and the engine operates,
the tank will have low pressure. This decreases fuel
supply and the power. When you open the fuel tank cap
you will hear the sound of air suction. Replace a clogged
filter.
6.5.7 To remove the filter for the fuel tank venting
• Remove the check valve and then the filter for the
fuel tank venting with a pair of pliers.
6.5.8 Function of the air purge bulb
The air purge bulb removes air from the fuel chamber of
the carburetor and fills it with fuel.
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