Evaporative Emissions System: Description and Operation

EVAP System Description
- The Evaporative Emission (EVAP) system prevents fuel vapor build-up in the sealed fuel tank. Fuel vapors trapped in the sealed tank are vented through the vapor valve assembly on top of the tank. The vapors leave the valve assembly through a single vapor line and continue to the EVAP canister for storage until the vapors are purged to the engine for burning.

EVAP System Operation
- The EVAP Running Loss System uses inputs from the Engine Coolant Temperature (ECT) sensor, the Intake Air Temperature (IAT) sensor, the Mass Air Flow (MAF) sensor, the Vehicle Speed Sensor (VSS) and the Fuel Tank Pressure (FTP) sensor to provide information about engine operating conditions to the PCM. The fuel level input (FLI) and FTP sensor signals to the PCM are used by the PCM to determine activation of the EVAP Monitor based on presence of vapor generation or fuel sloshing.