Evaporative Emissions System: Description and Operation

PURPOSE AND OPERATION
This system prevents fuel vapor from reaching the atmosphere. The system consists of a fuel expansion tank located between the inner right hand body side and rear right hand fender, and an adsorption canister located in the engine compartment attached to the front right hand valance.


When the fuel expands in the fuel tank due to temperature increase it is vented into the bottom of the expansion tank, any liquid fuel can be siphoned back into the main tank. Fuel vapor is directed as the fuel cools through the outlet pipe at the top of the expansion tank to the adsorption (charcoal) canister by means of a pipe running along the underside of the vehicle.


A restrictor located in the purge line at the plenum chamber controls purge line flow.


The adsorption canister containing activated charcoal is used to store fuel vapor from the fuel tank. Filter pads are fitted above and below the charcoal to prevent ingress of foreign matter of charcoal into the purge line. Emissions from the fuel tank enter the top of the canister and the purging air enters at the bottom. The canister is purged of its vapors by the vacuum generated within the plenum chamber, the vapor being drawn into the plenum chamber and burnt with the in-going mixture.









Evaporative Emission Control System