| Depending on air pressure and ambient temperature, more or less fuel fumes are generated above the surface of the fuel tank. |
| The activated charcoal filter system prevents these HC emissions from entering the air we breathe. |
| The fuel fumes, in a lesser quantity arrive at the activated charcoal filter from the highest point of the fuel tank through the gravity valve (which closes when it reaches a 45° inclination) and through the deaeration valve. |
| The activated charcoal absorbs these fumes like a sponge. |
| With the engine running and lambda control activated (warm engine), depending on the engine load and speed, the control unit excites the fuel tank deaeration valve -N80-, also called the regeneration valve, with impulses. The opening time depends on the signals received. |
| During the scanning process (activated charcoal regeneration) the ambient air that passes through the ventilation housing on the upper part of the activated charcoal filter is drawn out by descompression of the intake manifold. The temporarily accumulated fuel fumes and the ambient air in the activated charcoal are added, and dosified for combustion. |
| The deaeration valve prevents the combustion fumes from being drawn out of the fuel tank if the deaeration valve of the tank is open and there is decompression in the adjacent intake manifold. This guarantees a prior draining of the activated charcoal filter. |
| Without current (e.g. a wiring interruption) the fuel tank deaeration valve is closed. The activated charcoal filter will not empty. |
| The descompression hose that goes from the throttle control unit to the activated charcoal filter is also connected by a bypass to a valve in the engine block breather. In some partial load conditions, the retaining valve that is installed there prevents intake air from entering the engine sump. This is a general improvement in the ventilation of the engine sump. The bypass ensures the ventilation of the engine sump. |
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| The hose connections are fastened with strip or tightening clamps. |
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| Always replace tightening clamps with strip clamps. |
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| To install strip clamps, the use of the -T20029- pliers is recommended. |
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