Page 52 of 2000

ENGINE - 2AZ-FE ENGINE
00REG22Y
To Intake Manifold
Purge VSV
Purge Air
Line
ECMFuel Tank
Canister Filter
Fresh Air LineRefueling Valve
Canister Pump Module
Ve n t
Va l v e
Leak Detection Pump
& Pump Motor
Canister
Pressure SensorCanisterP M
EG-55
System Diagram
Function of Main Components
ComponentFunction
CanisterContains activated charcoal to absorb the vapor gas that is created in the
fuel tank.
Refueling
Controls the flow rate of the vapor gas from the fuel tank to the canister
when the system is purging or during refueling.
Refueling
Va l v eRestrictor PassagePrevents a large amount of vacuum during purge operation or system
monitoring operation from affecting the pressure in the fuel tank.
Fresh Air LineFresh air goes into the canister and the cleaned drain air goes out into
the atmosphere.
Vent ValveOpens and closes the fresh air line in accordance with the signals from
the ECM.
Canister
Pump ModuleLeak Detection
PumpApplies vacuum pressure to the EVAP control system in accordance
with the signals from the ECM.
p
Canister
Pressure SensorDetects the pressure in the EVAP control system and sends the signals
to the ECM.
Purge VSV
Opens in accordance with the signals from the ECM when the system
is purging, in order to send the vapor gas that was absorbed by the
canister into the intake manifold. In system monitoring mode, this valve
controls the introduction of the vacuum into the fuel tank.
Canister FilterPrevents dust and debris in the fresh air from entering the system.
ECM
Controls the canister pump module and purge VSV in accordance with
the signals from various sensors, in order to achieve a purge volume that
suits the driving conditions. In addition, the ECM monitors the system
for any leakage and outputs a DTC if a malfunction is found.
Page 53 of 2000

ENGINE - 2AZ-FE ENGINE
D13N07 285EG76
Chamber A
Fresh Air Line
Refueling
Valve (Open)
Chamber B
From Fuel
Ta n k
Internal PressureCanister
To F u e l
Ta n k
Positive Pressure
(Fuel Tank Pressure)
Restrictor PassageNegative Pressure
(Intake Manifold Pressure)
During Refueling During Purge Operation or
System Monitoring Operation
228TU119
Fuel Tank Cap
Fresh Air
Fuel Inlet PipeTo Canister
Cleaned Drain Air EG-56
Construction and Operation
1) Refueling Valve
The refueling valve consists of the chamber A, chamber B, and restrictor passage. A constant
atmospheric pressure is applied to the chamber A.
During refueling, the internal pressure of the fuel tank increases. This pressure causes the refueling
valve to lift up, allowing the vapor gas to enter the canister.
The restrictor passage prevents the large amount of vacuum that is created during purge operation or
system monitoring operation from entering the fuel tank, and limits the flow of the vapor gas from the
fuel tank to the canister. If a large volume of vapor gas recirculates into the intake manifold, it will
affect the air-fuel ratio control of the engine. Therefore, the role of the restrictor passage is to help
prevent this from occurring.
2) Fuel Inlet (Fresh Air Line)
In accordance with the change of structure of the EVAP control system, the location of a fresh air line
inlet has been changed from the air cleaner section to the near fuel inlet. The flesh air from the atmosphere
and drain air cleaned by the canister will go in and out of the system through the passage shown below.
Page 55 of 2000

ENGINE - 2AZ-FE ENGINE
00REG23Y
To Intake Manifold
Atmosphere
Purge VSV
(Open)
ECM
00REG24Y
CloseOpen EG-58
System Operation
1) Purge Flow Control
When the engine has satisfied the predetermined conditions (closed loop, engine coolant temperature
above 74
C (165F), etc.), the stored vapor gas are purged from the canister whenever the purge VSV
is opened by the ECM.
The ECM will change the duty ratio cycle of the purge VSV, thus controlling purge flow volume. Purge
flow volume is determined by intake manifold pressure and the duty ratio cycle of the purge VSV.
Atmospheric pressure is allowed into the canister to ensure that purge flow is constantly maintained
whenever purge vacuum is applied to the canister.
2) ORVR (On-board Refueling Vapor Recovery)
When the internal pressure of the fuel tank increases during refueling, this pressure causes the diaphragm
in the refueling valve to lift up, allowing the vapor gas to enter the canister. Because the vent valve is
always open (even when the engine is stopped) when the system is in a mode other than the monitoring
mode, the air that has been cleaned through the canister is discharged outside the vehicle via the fresh
air line. If the vehicle is refueled in the monitoring mode, the ECM will recognize the refueling by way
of the canister pressure sensor, which detects the sudden pressure increase in the fuel tank, and will open
the vent valve.