Evaporative Emissions System: Description and Operation

EVAP System:

PURPOSE
The fuel evaporative system captures and burns fuel vapors that would otherwise be vented into the atmosphere. The system consists of a separator, check-and-cut valve, two-way check valve, charcoal canister, purge control solenoid valve, powertrain control module (PCME) and its input devices.

OPERATION
Evaporative fumes are stored in a charcoal filled canister until purged into the engine intake system. The quantity of evaporative fumes entering the intake system is regulated by the PCME controlled solenoid valve to correspond to engine operating conditions. The PCME uses duty signals to the solenoid valve to allow charcoal canister purging under these conditions:
^ After warm-up
^ Driving in gear
^ Accelerator pedal depressed (idle switch OFF)
^ Oxygen sensor functioning normally