Evaporative Emissions - V6 S/C 3.0L Petrol (G1947221): Overview

WARNING: This page is about a different variant/trim than selected.

The Evaporative Emission (EVAP) control system reduces the level of hydrocarbons released into the atmosphere by fuel vapor venting from the fuel tank. The system comprises an evaporative emissions canister, purge valve and interconnecting vent pipes and hoses. The vent pipes are connected to the system components using quick release connectors.

On North American Specification (NAS) market vehicles, the system is checked for leak tightness by a Diagnostic Module Tank Leakage (DMTL) pump (part of the evaporative emissions canisters), which pressurizes the system and checks for leakage.

Fuel vapor is generated by the fuel in the tank and the amount of vapor produced increases as the fuel heats up. Fuel vapor can flow freely to the evaporative emissions canisters via the tank venting system. The venting system consists of a combined vent and rollover valve installed in the fuel tank. On all vehicles except NAS, the refueling breather pipes connect from the tank breather stub to the top of the fuel filler pipe, and the fuel tank vent system to the evaporative emissions canister. On NAS market vehicles, the fuel tank vent system connects into a refueling breather pipe that connects to the evaporative emissions canisters. NAS vehicles also have a communication line that connects the upper part of the filler pipe to the tank vent system.

The vapor from the fuel tank passes into the evaporative emissions canisters where it is absorbed and stored by the charcoal. Because there is a limit to the amount of vapor the canisters can contain, the fuel vapor is purged from the canisters when the engine is running and burned in the engine during the combustion cycle.

On NAS market vehicles the vapor generated in the fuel tank during refueling flows without restriction to the evaporative emissions canisters. On all vehicles except NAS, the vapor is restricted in its path to the evaporative emissions canister but can flow freely during the fuel filling operation to atmosphere, via the filler opening.