Audi A4

since 1994 of release

Repair and car operation



A4 Audi
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ exhaust System
+ cooling System
- Fuel tank and fuel pump
   For what ventilation of a fuel tank is necessary?
   The sensor of the indicator of level of fuel in a fuel tank
   Toplivoprovoda
   The fuel pump with the electric drive
   Dismantle of the petrol pump with the electric drive
   Replacement of the fuel filter
+ Air filter and absorption channels
+ injection System
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
+ Electrotechnical equipment
+ ignition System
+ Lighting
+ 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–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 supply 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 supply of fuel will stop.

Further the fuel tank should be ventilated in order that fuel had a possibility for expansion when heating. At the fuel gulf from a fuel tank air enough should be forced out in order 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 allowed at failures.
  • From there 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 harmful to environment fuel паров, acting through this tube (arising, for example, at the expense of heating of contents of a fuel tank). When the engine works, at certain load of it gases are again sucked away from the coal filter. When it occurs, defines the electromagnetic valve operated by injection of fuel.
  • Parallel to this system there is a high-speed ventilation which conducts to a jellied branch pipe through the compensating volume in the form of capacity of a special purpose in jellied mine of a fuel tank. This way of ventilation matters, first of all when filling when fuel level quickly rises, and fuel pairs should be forced out but so that not to get to the atmosphere in too large number.
  • During movement by the same way to a fuel tank atmospheric air according to spent fuel therefore in a fuel tank the lowered pressure cannot be formed gets.