Suzuki UG110 2021, Service Manual, Page: 78 / 198

4-2 FUEL AND LUBRICATION SYSTEM
FUEL SYSTEM
The fuel pump is operated by a vacuum force which is supplied from the crankcase. The fuel sent under
pressure by the fuel pump flows into the float chamber when the float of the carburetor has dropped and the
needle valve is open. When the needle valve closes, the pressure of the fuel in the hose connecting the
carburetor and the fuel pump increases, and when the set pressure is reached, the operation of the fuel pump
is stopped by the fuel pressure to prevent excessive supply.
FUEL PUMP
Vacuum pulsations from the crankcase are used to operate the pump diaphragm
A
. When vacuum is applied
to the diaphragm
A
, fuel is drawn from the fuel valve into the diaphragm’s chamber
B
. As positive pressure
is applied, the diaphragm backs, pushing the fuel through the outlet to the carburetor.
A series of check valves (
1
and
2
) is used in the fuel flow route to allow the fuel to move in only one
direction, through the pump body.
To crankcase
From fuel valve
To carburetor
From fuel valve
From crankcase
FUEL
If the fuel pressure in the chamber of carburetor side is too high,
the return valve
3
is opened so that the fuel pressure is released
to the chamber of fuel valve side.