Fuel tank ventilation system in the Audi-100
The fuel tank vent pipe is connected to the fuel level sensor. A pressure valve is built into this pipeline. Next, the pipeline is brought to the tank with activated carbon. Overpressure (from 0.2-0.3 bar) the valve closes and when refueling prevents fuel from entering the activated charcoal tank.
After passing through this valve, however, the ventilation line does not lead directly to the outside, but ends in the activated charcoal reservoir in the right front wheel housing. Its purpose is to catch fuel vapors passing through this pipeline (arising, for example, as a result of heating the contents of the fuel tank). When the engine is running, these gases are again sucked out of the activated charcoal tank under a certain engine load. When this should happen, determines the load-controlled solenoid valve.
Also, the activated charcoal tank needs to be ventilated from below. The next valve regulates this process and also prevents water splashes from entering.
The illustration shows individual parts on the inside and outside of the fuel tank:
1 - filling pipe;
2 - nozzle for the filling pipe;
3 - fuel tank;
4 - retaining ring;
5 - fuel level sensor (with locking flange);
6 - fuel accumulator (only in vehicles with injection system KE-lll-Jetronic or KE-Motronic);
7 - fuel pump with air intake housing.
The solenoid valve for the activated charcoal tank is located in vehicles with the KE-lll-Jetronic or KE-Motronic injection system at the front on the fuel dispenser.
Regardless of the aforementioned fuel tank ventilation system, there is an emergency vent line directly in the filler pipe. It only prevents fuel from spilling out when refueling.
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