Toyota Camry Hybrid AHV40 Manual page 239

10. Evaporative Emission Control System
General
D The evaporative emission control system on the '07 Camry Hybrid model consists of the fuel
vapor-containment system (to prevent fuel vapor escaping into the atmosphere), the purge flow control
(to purge fuel vapor), and the EVAP leak check (to check for leakage from the evaporative emission
control system).
D The fuel vapor-containment system prevents the fuel vapor from escaping from the fuel tank when the
engine is stopped (and the vehicle is parked).
D THS II controls the engine to make it operate intermittently, making the operation time of the engine
shorter than that of conventional gasoline engine models. Due to the engine being unable to burn the fuel
vapor sufficiently, the fuel vapor that is created exceeds the capacity of normal-sized canisters.
Therefore, the fuel vapor-containment system releases the fuel vapor from the fuel tank only when the
engine is running, and burns it in the engine, in order to comply with the AT-PZEV emission regulations.
Evaporative
Emission Control
Fuel Vapor-
containment
System
Purge Flow Control
EVAP Leak Check
ENGINE - 2AZ-FXE ENGINE
D When the vehicle is parked (with engine stopped), the system closes the fuel
vapor-containment valve to seal the fuel tank.
D For refueling, the system opens the fuel vapor-containment valve, allowing the
fuel vapor to be absorbed by the canister and reducing the pressure in the fuel
tank.
D When the engine is operating, the system controls the fuel vapor-containment
valve to release the fuel vapor and effect purge flow control.
Opens the purge VSV when the engine is running, allowing the engine vacuum
to draw the fuel vapor absorbed by the canister and burn it in the engine.
The THS ECU opens the fuel vapor-containment valve when the purge VSV is
open and the internal pressure of the fuel tank is high. Thus, the fuel vapor in the
fuel tank and the fuel vapor absorbed by the canister are drawn into the engine
to be burned.
When the engine is stopped, the THS ECU operates the canister pump module
to perform a leak check in the evaporative emission control system and check the
functions of the parts.
Depending on the internal pressure of the fuel tank, the THS ECU performs two
types of leak check operations:
D When the internal pressure of the fuel tank is equal to the atmospheric pressure.
D When the internal pressure of the fuel tank is higher [3 kPa (0.03 kgf/cm
psi) minimum] or lower [-2 kPa (0.02 kgf/cm
atmospheric pressure.
Outline
2
, -0.29 psi) maximum] than the
EG-51
2
, 0.44