G424 Service Manual
Gasoline Fuel System
63
5. Enrichment system
The enrichment system provides additional fuel
feed to the main metering system during high-
speed large-torque operation.
This system use the membrane (diaphragm) which
is actuated by the intake manifold vacuum and
membrane spring to open or close the fuel feed
line.
During partial-throttle operation, a large manifold
vacuum is applied to the vacuum chamber through
the vacuum line and acts on the membrane to close
the valve against the membrane spring force.
When the throttle is opened wide, manifold vacuum
decreases.
This allows the membrane spring to open the valve.
Now, more fuel from the float chamber is metered
by the enrichment jet and can flow through the
valve into the primary main line leading to the main
metering system.
6. Accelerator-pump system
Rapid opening of the throttle for acceleration allows
a sudden inrush of air. Thus there is a sudden
demand for additional fuel. To provide this extra
fuel, the accelerator-pump system can feed fuel
immediately under pressure.
Fuel from the inlet check valve is sent to the pump
nozzle through the outlet check valve by
reciprocating movement of the membrane. The fuel
is then injected into the main bore.
When the engine is accelerated quickly, the
membrane is pushed by the pump lever linked to
the throttle valve and forces fuel to flow under
pressure. When the engine is decelerated, the
membrane is pushed back by the spring and the
pump chamber is refilled with fuel.
Pump delivery decreases with engine speed from
which acceleration is starred. It does not deliver fuel
at all when the angle of throttle valve from the idling
position exceeds the preset angle.
7. Stating system
The starting system consists of the choke valve,
lever assembly, choke connecting rod, and choke
operating lever. This system is provided for feeding
a very rich air-fuel mixture to the engine when the
engine is started (until the engine warms up) or
when a temporary increase of output is needed
during engine operation. When the engine is cold,
some throttle opening must be maintained so that
the engine idles faster then it would when warm.
This is done with “fast idle.” With the fast idle, the
choke valve is closed while the throttle valve is held
at a partially opened position most suitable to
warming-up run.
Enrichment and Accelerator-Pump systems
Содержание G424 Gasoline
Страница 24: ...G424 Service Manual Engine System 23 Gasoline Engine ...
Страница 25: ...G424 Service Manual Engine System 24 LPG Engine Low Emission Version ...
Страница 30: ...G424 Service Manual Engine System 29 LPG Engine Low Emission Version ...
Страница 32: ...G424 Service Manual Engine System 31 Wiring Diagram LPG Engine Low Emission Version ...