Evaporative emission control - ’K’ series

Evaporative emission control - ’K’ series

1. Throttle disc
2. Fuel cut-off valve
3. Two way valve
4. Evaporative emission canister

The evaporation emission control system is used to reduce the level of hydrocarbons emitted into the atmosphere from the fuel system. The system comprises a carbon canister which stores the hydrocarbons from the fuel tank, pressure valves, vent lines and a purge control solenoid valve.

Fuel vapour generated from within the fuel tank as the fuel heats up is stored in the tank until the pressure exceeds the operating pressure of the two-way valve. When the two way valve opens, the fuel vapour passes along the vent line from the fuel tank (via the fuel tank vapour separator) to the inlet port of the carbon canister.

5. Evaporative emission canister purge valve
6. Fuel filler cap
7. ECM
8. Fuel trap

Fuel vapour is stored in the canister until it is ready to be purged to the inlet manifold under the control of the Engine Control Module (ECM).

As fuel vapour cools, it condenses and is allowed to flow back into the fuel tank from the vent line by way of the two-way valve. A fuel vapour separator is fitted next to the fuel filler neck. This separator allows condensing fuel in the fuel tank to be returned to the tank before it reaches the vent line.