Husqvarna 543RBX Workshop Manual page 24

and throttle valve (A) are found here. The main jet is in
the middle of the venturi.
A
Pump unit
This is where the pump diaphragm (A) that supplies fuel
to the metering unit from the fuel tank is found. The
24 - Repair instructions
diaphragm is operated by pressure variations in the
engines crankcase through an impulse channel (B). If
the impulse channel is blocked, by grease or an
incorrectly installed gasket, the pump unit does not
operate.
B
A
B
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