Toyota 77740-07020 Canister Assy, Charcoal

The evaporative emissions control system draws fuel vapors from the fuel tank and fuel system, stores them in a charcoal canister, then burns them during normal engine operation. The most frequent sign of problems with the evaporative emissions system is strong smell of gas within or near the car. If you notice smell of gasoline, examine charcoal canister. Inspect for any damage or deterioration to all hoses and canister. The canister lies aft of the vehicle above suspension crossmember. More information about this system will be provided elsewhere.

The fuel evaporative emissions control (EVAP) system absorbs fuel vapors and releases them into the engine intake during operation, where they mix with the incoming air-fuel mixture. The charcoal canister, located behind the fuel tank under the vehicle, stores fuel vapors when the engine is not running, transferring them from the fuel tank, throttle body, and intake manifold. When the engine operates, the purge control valve purges the vapors from the canister, allowing them to be consumed in the combustion process, with the electronic valve controlled by the PCM. A two-way valve on the fuel filler cap vents vapors to the atmosphere if the EVAP system fails, while a vapor pressure sensor detects abnormal pressure in the system, mounted in the fuel pump/sending unit assembly atop the fuel tank. Once the engine reaches a pre-set temperature, the Vacuum Switching Valve (VSV) opens, allowing intake manifold vacuum to draw vapors from the canister for combustion. The vapor pressure sensor monitors tank pressure and opens the VSV when a preset threshold is exceeded, admitting fuel tank vapors into the canister. To replace the charcoal canister, disconnect the cable from the negative battery terminal, raise the rear of the vehicle and support it securely on jackstands, unplug all electrical connectors, label and disconnect the vent hoses, remove the bolts, and separate the canister from the vehicle's underside, with installation being the reverse of removal.

The EVAP canister purge valve is located behind the air filter housing on four-cylinder models and on the left end of the front bank cylinder head on V6 models.

The most common symptom of a fault in the evaporative emissions system is a strong fuel odor in or around the vehicle.