| A greater or smaller quantity of fuel vapours form above the level of the fuel in the tank - depending on the atmospheric pressure and ambient temperature. |
| The activated charcoal filter system prevents these HC emissions escaping into the air we breath. |
| The fuel vapours flow from the highest point of the fuel tank through the gravity valve (is connected at an angle of 45°) into the activated charcoal filter. |
| The activated charcoal absorbs these gases in the same way as a sponge. |
| When driving with the lambda control active (engine warm), the solenoid valve -N80- (also known as purge control or regeneration valve) is actuated (pulsed) by the engine control unit in line with engine load and speed. The opening time is dependent on the incoming signals. |
| During the purging process (regeneration of the activated charcoal) fresh air is inducted as a result of the vacuum in the intake manifold, through the air admission opening on the bottom of the activated charcoal tank. The fuel vapours and fresh air absorbed by the activated charcoal are metered back to the combustion process. |
| The pressure holding valve prevents fuel vapours being drawn out of the fuel tank when the solenoid valve on the activated charcoal filter system is opened and adequate intake manifold vacuum is present. It thus ensures that priority is given to emptying the activated charcoal tank. |
| The solenoid valve is closed when de-energized (e.g. open circuit in wiring). The activated charcoal tank is not emptied in this case. |
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| The hose connections are secured using spring-type clips or quick couplings. |
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| Always replace clamp-type clips with spring-type clips. |
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