Fuel Evaporation System: Operation
When engine is not running, vapor from fuel tank flows to charcoal canister. When ignition is off, float bowl (carburetor only) is vented to canister. Check and cut valve (3-way valve) prevents excessive pressure or vacuum from forming in system.
When coolant reaches 131°F (55°C) on MX-6, 626 and B2600 or 129°F (54°C) on B2200, coolant thermovalve opens. On 323, ECU controls the system. When manifold vacuum opens purge control valve, fresh air enters bottom of charcoal canister. Vapor is drawn into engine.
On 929, a coolant temperature sensor signals ECU when engine is warm. When coolant 158°F (70°C) and engine is at idle, the No. one 3-way solenoid valve is energized. Fuel vapors will be drawn through restrictor orifice "A". With engine warm and engine speed above 1500 RPM, No. 2 3-way solenoid valve is energized by ECU. Additional fuel vapors will now by-pass restrictor orifice "A".