CAC Gasoline Engine Maintenance And Servicing Manual
95
If the pressure in the fuel tank (1) rises beyond the specified value, two-way check valve (2) will open
reducing the pressure in the fuel tank.
If necessary, the valve may open reversely to vent inward when the fuel tank is vacuumed.
—When the fuel level is at middle or low , when it exceeds a specified pressure, the multi-function valve
(4) will permit the fuel vapor to reach the charcoal canister (6) and be absorbed by the activated carbon
granule.
The operation when engine is running (figure. 155)。
Solenoid (7) is powered on by ignition switch and is controlled by the injection system ECU directly by
the following modes: When the valve is open, the vacuum in engine will suck the vapor collections in the
charcoal canister into the lower part of throttle valve. When powered off, the valve will close to prevent theλ
sensor from sucking the vapor when it doesn’t work.
8 fuel vapor recirculation solenoid valve (condensing chamber EC1)
the fuel vapor recirculation solenoid valve is designed to regulate the vapor volume(from the charcoal
canister) controlled by ECU. When the solenoid valve is deenergized ,the valve closes.
Its operation is controlled by ECU as following:
·Under the starting condition , the solenoid keeps close
preventing the fuel vapor from richening the mixture until the
specified engine coolant temperature is reached.
·during engine’s running, ECU sends a square wave signal to
the solenoid. The signal is used to control the fuel vapor
recirculation valve by energizing or deenergizing it. By this way,
ECU controls the fuel vapor volume to intake manifold preventing
the mixture density from changing dramatically.
·under a specified working condition：
—— the throttle
valve is at idling position
—— speed is
lower than the specified
—— the solenoid does not function When the intake pipe
pressure is lower/ higher than the specified value, the solenoid
remains close to improve the engine performance.
—— fuel cut-off switch
the switch is located in the right side of driver. It will cut
off the fuel supply for the injection system by switching off
the ground wire for fuel pump..
Fig.155 solenoid
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