Husqvarna K970 SmartGuard Workshop Manual page 39

6.6.4 Pump unit function
The pump diaphragm (A) receives power by changes of
pressure in the crankcase. The pressure changes are
caused by the piston movement and transmitted to the
top of the pump diaphragm. The fuel below the
diaphragm is pushed to the valves (B). Pressure from
the measurement chamber diaphragm to the needle
valve in the measurement chamber controls how much
the valve opens. It also controls the quantity of fuel
transmitted to the fuel side of the measurement
chamber.
B
6.6.5 To examine the fuel pump diaphragm
1. Connect the pressure tester to the fuel line.
2. Increase the pressure to to a maximum of 36 psi/ 2.5
bar.
A
If air comes out of the impulse channel (A), the pump
diaphragm is broken.
6.6.6 Function of the measurement chamber
The product has SmartCarb
measurement chamber has an air chamber to the cover
and a fuel chamber to the carburetor body. The air
chamber and the fuel chamber are divided by the
1451 - 001 - 02.04.2020
A
B
™
filter compensation. The
measurement chamber diaphragm. The diaphragm
controls and keeps a constant level of fuel in the fuel
chamber through the mechanically connected needle
valve. The air chamber is near the inlet, after the air
filters, and gives the air chamber the same pressure.
You cannot examine the chamber diaphragm with a
pressure check. To examine the diaphragm, refer to
examine the measurement chamber diaphragm on page
39 . A hole in the diaphragm stops the fuel supply.
6.6.7 To examine the measurement chamber
diaphragm
1. Remove the 4 screws and disassemble the
measurement chamber.
2. Examine the chamber diaphragm visually. Fuel on
the top side, against the cover, is a sign of leaks. If
there is fuel on the top side, replace the chamber
diaphragm.
To
Repair and servicing - 39