Exhaust emission control. (page 2 of 3)

EVAPORATIVE EMISSION CONTROL SYSTEM A pressure relief valve is fitted in the hose which is open to atmosphere. This valve acts as a safety valve The system is designed to prevent harmful fuel vapour should a build-up of pressure occur in the system, for from escaping to the atmosphere. The system example if a hose became blocked or kinked. The consists of a vapour separator tank, connected to the volume of vapour emitted, in such an instance, would fuel tank and located between the body inner and be limited. outer panels on the right hand side of the vehicle near the rear wheel arch. An Evaporative Emissions A pressure relief valve is also fitted in the hose (EVAP) canister, containing activated charcoal, is connected to the adsorption canister and releases positioned in the engine compartment attached to the vapour to the canister when the pressure in the front right valance. The two components are separator reaches between 5 and 7 Kpa (0.7 and 1.0₂ connected by a pipe running the length of the chassis. lbf/in ).

In the top of the separator a shut-off valve is

incorporated in the vapour exit port to prevent the possible presence of any liquid fuel being transmitted to the EVAP canister should the vehicle roll over.

The EVAP canister, which is connected by a hose to the plenum chamber, absorbs and stores the fuel vapour from the fuel tank while the engine is not running. When the engine is started, the vapour is purged from the canister by air drawn through an orifice in the base of the canister and by the influence of vacuum at the top. The vapour drawn into the plenum chamber through a solenoid operated purge valve is finally burnt in the combustion chambers.

The purge valve, which is attached to the EVAP

A Pressure relief to atmosphere.

canister support bracket, is controlled by the Engine

B From fuel tank to separator.

Control Module ECM which determines the optimum

C To evaporative emissions canister.

time at which purging should take place. This will

D Pressure relief valve.

normally be at engine speeds above idle and when

E Pressure relief valve.

the vehicle is in motion. A signal from the ECM to the

F Shut-off valve.

purge valve operates the solenoid and opens the

G "Speed Fit" connectors.

valve to purge the canister of fuel vapour.