Evaporative Emissions System: Description and Operation

DIGIFANT II




Evaporative Emission System

The carbon canister stores fuel vapors from the fuel tank when the engine is off. During normal driving, fuel tank vapors are drawn into the throttle housing via the carbon canister control valve.

The illustration (left) shows the flow of fuel tank vapors with the throttle open (vacuum supplied to the control valve). The vapors are drawn into the throttle housing via a 1.2 mm orifice (restrictor).

The vacuum source for the control valve is before the throttle plate. This means that when the throttle is closed, the carbon canister is not purged. Therefore, when setting C0%, it is not necessary to disconnect the carbon canister vent line.