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Evaporative emission system

Evaporative emission system

General

Hydrocarbons from the fuel tank ventilation pass through a tube to a container filled with active coal (evaporative emission canister) for intermediate storage. Fuel vapour is then drawn via the evaporative emission canister purge valve into the engine for combustion.

The evaporative emission canister purge valve is controlled by the ECM and the flow is regulated by the pulse ratio so that it always constitutes a certain amount of the total flow consumed by the engine.

Brief description

Evaporative emission canister

The evaporative emission canister comprises a container with active coal, which is used for intermediate storage of fuel vapour from the tank. In the container are connections for the intake from the tank and the outlet to the evaporative emission purge valve. There is also an opening for fresh air, through which air is drawn via the coal for cleaning and into the intake manifold.

To prevent carbon powder penetrating the evap canister purge valve and causing a leak, the evaporative emission canister has a fine-mesh sieve in the upper part.

Evaporative emission canister cleaning

When the engine starts, the surrounding air is drawn through the evaporative emission canister into the intake manifold. It takes fuel vapour with it for combustion in the engine.