California Models Only
All California models are fitted with a system to control the evaporation of fuel vapour to the atmosphere.
A carbon filled canister absorbs vapour while the engine is not running. When the engine is started, the vapour is returned to the engine and burnt.
There are two distinct phases to the system's operation, engine off and engine running. These two conditions are explained overleaf.
Component Locations
Carbon Filled Canister (2) - below the swinging arm.
Purge Control Valve (3) - adjacent to frame, left hand side (electronically controlled by the ECM).
1. Breather hoses; 2. Carbon filled canister; 3. Purge valve; 4. Purge hose to throttle bodies; 5. Fuel tank filler drain
Evaporative Control System - Engine Off
When the engine is stationary any pressure increase in the fuel tank due to a rise in ambient temperature will cause the fuel vapour to pass down the breather hose (1) to a carbon filled canister (2) which stores the vapour.
Once in the canister, vapour cannot enter the engine because the purge valve is closed.
1. Breather hoses; 2. Carbon filled canister; 3. Purge valve (closed}; 4. Purge hose to throttle bodies; 5. Fuel tank filler drain
Evaporative Control System - Engine Running
When the engine is running, engine vacuum is applied to the purge hose (4) from the throttle bodies.
At certain times, the ECM opens the purge valve. The vacuum applied to the purge hose (4) now begins to draw stored vapour from the carbon filled area of the canister and returns it to the throttle bodies for burning in the engine.
In order to control the speed at which vapour is purged from the canister, the engine management system shuttles the purge control valve between open and closed positions.
1. Breather hoses; 2. Carbon filled canister; 3. Purge valve (open under ECM control); 4. Purge hose to throttle bodies; 5. Fuel tank filler drain