Evaporative Emissions System: Description and Operation

Fig. 16 Purge Control System Schematic:

CARBON CANISTER

While the engine is not running fuel vapors generated inside the fuel system are absorbed and stored in the carbon canister. When the engine is started once again the ECU will purge the fuel vapors from the carbon canister to the engine intake.

PURGE CONTROL SOLENOID VALVE

The purge control solenoid valve is an electrically operated valve controlled by the ECU that permits purging of the carbon canister. The ECU will operate the purge control solenoid valve only when engine speed exceeds 3000 rpm and coolant temperature exceeds 70 degrees C or 158 degrees F.

Fig. 52 Overfill Limiter Valve:

OVERFILL LIMITER VALVE

The overfill limiter valve is a two way valve. It relieves pressure build up in the fuel tank into the purge system and relieves vacuum build up in the fuel tank by allowing fresh air into the fuel tank.