Audi A4

Since 1994 of release

Repair and car operation



Audi А4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ Exhaust system
+ Cooling system
- Fuel tank and the fuel pump
   For what ventilation of a fuel tank is necessary?
   The gauge of the indicator of level of fuel in a fuel tank
   Топливопроводы
   The fuel pump with the electric drive
   Dismantle of the petrol pump with the electric drive
   Replacement of the fuel filter
+ The air filter and channels всасывания
+ Injection system
+ Coupling
+ Transmission and the main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tyres
+ The electrotechnical equipment
+ Ignition system
+ Illumination
+ The alarm equipment
+ Tools and devices
+ Heating and ventilation
+ Body details
+ Salon
Search of malfunctions
Technical characteristics



For what ventilation of a fuel tank is necessary?

The electromagnetic valve of the coal filter is at the left below behind in an impellent compartment

1 – a tube to the coal filter;
2 – the electromagnetic valve;

3 – electric connection;
4 – a tube to an inlet collector of the engine.


The coal filter (2) is behind in the right forward wheel niche. Further are visible: a tube to the electromagnetic valve (1), a tube to ventilation of a fuel tank (3).

Ventilation of a fuel tank is important for faultless giving of fuel: in that volume in what fuel is spent, air should get into a fuel tank, differently in a fuel tank the lowered pressure is formed, and fuel giving will stop.

Further the fuel tank should be ventilated that fuel had a possibility for expansion at heating. At a gulf of fuel from a fuel tank air enough should be superseded that filled in fuel did not pour out through a jellied branch pipe.

Ventilation of a fuel tank in Audi A4

  • Above in a fuel tank the ventilating tube is connected. In the beginning it goes through connecting knot on a jellied branch pipe to the so-called gravitational valve. It closes a tube as soon as the car bends sideways more than on 45 . In such a way fuel pouring out through a ventilating tube is not supposed at failures.
  • Therefrom the ventilating tube is deduced not simply outside, and enters into the coal filter in the right forward wheel niche. The purpose of such device consists in catching of the fuel steams harmful to environment acting through this tube (arising, for example, at the expense of heating of a contained fuel tank). When the engine works, at certain loading on it gases again are sucked away from the coal filter. When it occurs, defines the electromagnetic valve operated injection of fuel.
  • In parallel this system there is a high-speed ventilation which conducts to a jellied branch pipe through the compensating volume in the form of special purpose capacity in jellied mine of a fuel tank. This way of ventilation matters, first of all at refuelling when fuel level quickly rises, and fuel steams should be superseded but so that not to get to atmosphere in too considerable quantity.
  • During movement by the same way to a fuel tank atmospheric air according to spent fuel gets, therefore in a fuel tank the lowered pressure cannot be formed.