Evaporative Emissions: Introduction

WARNING: This page is about a different car, the 2011 Jaguar XKR, 2011 Jaguar XK, 2010 Jaguar XKR, and 2010 Jaguar XK. However, it is still accessible from the selected car via links, so may be relevant.

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

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 emission (EVAP) canister via the tank venting system.

On NAS vehicles the vapor generated in the fuel tank during refueling flows without restriction to the evaporative emission (EVAP) canister.

On all vehicles except NAS, the vapor is restricted in its path to the evaporative emission (EVAP) canister, but can flow freely during the refueling operation to atmosphere via the fuel filler pipe opening.

The vapor passes into the evaporative emission (EVAP) canister where it is absorbed and stored by the charcoal. Because there is a limit to the amount of vapor the canister can contain, the fuel vapor is purged from the canister when the engine is running and burned in the engine.