05-09-2012, 02:41 PM
EVAPORATIVE EMISSION CONTROL SYSTEM
07. Evaporative Emission Control System.pdf (Size: 249.17 KB / Downloads: 125)
GENERAL
The evaporative emission control system prevents fuel vapors from escaping into atmosphere.
This system includes a canister, purge control solenoid valve, fuel cut valve, and the lines connecting
them.
Fuel vapors in the fuel tank is introduced into the canister through the evaporation line, and are
absorbed by activated carbon in it. The fuel cut valve is also incorporated in the fuel tank line.
The purge control solenoid valve is controlled optimally by the ECM according to the engine condition.
The pressure control solenoid valve incorporated in the fuel tank evaporation line regulates the
pressure/vacuum in the fuel tank under the control of the ECM which uses the signal from the fuel
tank pressure sensor.
The diagnosis of the evaporative emission control system is performed by turning each solenoid
valve ON/OFF to vary the pressure inside the fuel tank and measure this pressure change with the
fuel tank pressure sensor in order to check for leaks and proper valve operation.
FUEL TANK CAP
The fuel tank cap has a relief valve which prevents development of vacuum in the fuel tank in the
event of a problem with the fuel vapor line.
When there is no problem with the fuel vapor line, the filler pipe is sealed at the portion (A) and by
the seal pressed against the filler pipe end. If vacuum develops in the fuel tank, the atmospheric
pressure forces the spring down to open the valve; consequently outside air flows into the fuel tank,
thus controlling the inside pressure.