Kubota WG972-E2 Workshop Manual page 59

WG972-E2, DF972-E2, WSM
■ Vacuum Lock Chamber
1) Operation when engine stops
Because pressure on the vacuum lock chamber (3)
side and the secondary chamber (4) side is equal,
vacuum lock diaphragm (5) is pushed to the second
chamber side by the tension of vacuum lock diaphragm
spring (2).
Secondary valve and the seat are made to close as
vacuum lock diaphragm pin (6) pushes secondary valve
lever (7) and the fuel leakage is prevented.
2) Operation at engine starting
The negative pressure is caused in inlet manifold at
the same time as the cranking's beginning.
This negative pressure acts in vacuum lock chamber
(3) and vacuum lock diaphragm (5) is drawn to the
vacuum lock chamber side.
As a result, the movement of secondary valve lever
(7) becomes free and the fuel inflow adjustment due to
secondary valve (1) becomes possible.
The negative pressure in inlet manifold always works
while the engine is rotating and the movement of
secondary valve lever is tuned to the movement of
secondary diaphragm.
(1) Secondary Valve
(2) Vacuum Lock Diaphragm
Spring
(3) Vacuum Lock Chamber
(4) Secondary Chamber
M-19
GASOLINE / LPG ENGINE
(5) Vacuum Lock Diaphragm
(6) Diaphragm Pin
(7) Secondary Valve Lever
W1029583
KiSC issued 01, 2006 A