212 ENGINE 273 MPFI Components of Evaporative Emission Control System Roll Over Valve in built with Fuel Module (Refer Fuel Module) Carbon Canister A canister made of high grade Nylon, containing special dust free activated carbon is used to absorb fuel vapours. The upper end of the canister is open to atmosphere for ventilation. The end is not really open but there is foam filter. The purpose of the bottom filter is to protect the canister from dust and dirt during operation. EVAPORATIVE EMISSION CONTROL SYSTEM Objective The car is fitted with an evaporative system to meet all requirements of evaporative emission. The system is designed to prevent fuel vapours formed within the tank and fuel system from escaping into the atmosphere. General Operation Of Evaporative Emission Control System The system operates when atmospheric temperature is higher, after the vehicle has been parked / standstill for a long time; the fuel temperature rises and brings about a pressure rise inside the tank. This rise may occur with medium - low fuel levels or with the tank full condition during tank refilling, the pressure inside is more or less same as atmosphere pressure. The breather port on fuel tank is connected to the filler neck which allows tank breathing during fuel filling. When the fuel filler cap is closed, it seals the system, the vapours generated inside the tank (with vehicle moving or while parked) due to fuel volatility, tank internal pressure builds up until the rollover valve opening level is exceeded. When the engine is inoperative, (i.e. while parked), fuel vapour generated inside the fuel tank due to fuel volatility are absorbed and stored in the canister. When the engine is running, the fuel vapours get absorbed in the canister after which they are purged into the intake manifold through canister purge valve operated by the ECU. Removal & Fitment: 1. Disconnect hoses from canister to purge valve. 2. When the air is blown into tank port, there should be no restriction of flow through purge port andAir port. 3. If the operation differs from the above description, canister must be replaced. 4. Connect hoses to canister. 5. Ensure that hoses are clamped securely. When the engine is inoperative (i.e. while parked) fuel vapours generated inside the fuel tank due to fuel volatility are absorbed and stored in the canister through tank pressure valve. When the engine is running, the fuel vapours absorbed in the canister are purged into intake manifold through canister purge valve operated by ECU. The purging takes place due to air drawn through the canister because of pressure differential between manifold vacuum and atmosphere.
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