Hyundai 31420-1R500 Canister Assembly-Fuel

The purpose for the evaporative emission control system is to keep fuel vapors from escaping into the atmosphere. It includes a canister, water vent valve, purge control valve, thermo valve, overfill limiter and specialty designed fuel cap. When the engine is off, the canister will absorb and store the vapors of the fuel system whereas when it's started; these vapors go through various valves and lines into intake manifold. Bowl vent valve controls carburetor float bowl vapors. The carbureted engine purge control valve is closed during idle to prevent vaporized fuel from entering the intake manifold. At higher engine speeds, the purge control valve opens. Thermo valve senses temperature at the intake manifold and closes purge control valve when coolant temperature falls below preset value. Fuel filler cap is fitted with vacuum relief valves to prevent escape of fuel vapor into atmosphere. There are two types: pressure valve which opens if internal pressure of a tank exceeds normal pressure condition while vacuum valve operates when internal tank pressure is lower than normal pressure condition.The fuel check-valve connected in fuel vapor line between canister and overfill limiter prevents leakage of fuel during vehicle rollover.It has two balls inside.Under normal conditions, it allows passage of fuel vapour through its body.However,in case of an accident,the balls will situate themselves in such a way that one blocks up this passage consequently preventing any possible leaking of petrol.