Volkswagen Touareg (2003 year). Manual - part 31

touching, with commercially available leak detector spray or

ultrasonic tester -V.A.G 1842- .

Caution

After completing work check tyre pressure!

Touareg 2003 ➤

3. Activated charcoal filter system    

121

Activated charcoal filter system (ve‐

hicles for USA and Canada)

Assembly overview - activated charcoal filter system

⇒ page 123

 .

Checking fuel system for leaks 

⇒ page 124

 .

Function
Fuel vapour forms above the surface of the fuel in the fuel tank;

the quantity depends upon the air pressure and ambient temper‐

ature.
The activated charcoal filter system prevents these HC emissions

escaping to the atmosphere.
Fuel vapours pass from the highest point in the tank (on filler neck)

through the expansion tank and into the activated charcoal filter.
The activated charcoal stores these vapours like a sponge.
When the vehicle is being operated and the Lambda control is

active (engine warm), the activated charcoal filter system sole‐

noid valve 1 -N80- is activated (pulsed) by the engine control unit

-J623- depending on load and engine speed. The opening period

depends on the input signals.
During the purging procedure (regeneration of activated char‐

coal), the intake manifold vacuum draws fresh air through the vent

of the activated charcoal filter. The fuel vapours stored in the ac‐

tivated charcoal and fresh air are fed to combustion in metered

quantities.
The activated charcoal filter solenoid valve 1 -N80- is closed when

it is not supplied with current (e.g. open circuit). The activated

charcoal filter will not be purged.
Description of leakage diagnosis
The activated charcoal filter system, including fuel tank, is equip‐

ped with leakage diagnosis which can detect if there is a leak in

the system.
The diagnosis is based on a pressure method and indicates leaks

with a diameter greater than 0.5 mm.
During the diagnosis, the fuel system diagnostic pump -V144-

builds up pressure in the activated charcoal system. For this, the

activated charcoal filter solenoid valve 2 -N115- is closed. Once

the pressure is attained, the pump switches off. If the pressure

drops below a certain value, the pump switches on again. Self-

diagnosis monitors the intervals at which the pump is switched on

or off and if the intervals are too short, writes a fault to the fault

memory.

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122

♦

Hose connections are secured with either spring-type or

clamp-type clips.

♦

Use spring-type clip pliers -VAS 6340- for installation of spring-

type clips

♦

or space-saving hose clip pliers -VAS 6362- .

Observe safety precautions 

⇒ page 99

 .

Observe rules for cleanliness 

⇒ page 99

 .

4.1

Assembly overview - activated charcoal filter system

1 - Expansion tank

❑ Right side.

2 - Gravity valve
3 - Fuel filler neck
4 - 5 Nm
5 - Bracket
6 - Vacuum line

❑ For vacuum supply of

fuel system diagnostic

pump -V144-

❑ To vacuum connection

on intake manifold

❑ Check for secure seat‐

ing.

7 - Fuel system diagnostic

pump -V144-

❑ Checking fuel system

for leaks 

⇒ page 124

 .

❑ Black connector, 3-pin

8 - Connecting hose

❑ Between air filter, fuel

system diagnostic pump

-V144- and activated

charcoal filter solenoid

valve 2 -N115-

❑ Check for secure seat‐

ing.

9 - 5 Nm
10 - Air filter

❑ Clean if soiled.

11 - Rubber bush

❑ Note installation position.
❑ Renew if damaged.

12 - Activated charcoal filter solenoid valve 2 -N115-

❑ Black connector, 2-pin

13 - Activated charcoal filter

❑ Location: in rear right wheel housing.

Touareg 2003 ➤

4. Activated charcoal filter system (vehicles for USA and Canada)    

123

❑ Qty. 3
❑ 9 Nm

15 - Breather line

❑ To vacuum connection on intake manifold
❑ Check for secure seating.

16 - Connector

❑ Black, 2-pin.

17 - Activated charcoal filter solenoid valve 1 -N80-

❑ Note installation position.

18 - Rubber bracket

❑ Note installation position.

19 - Breather line

❑ Check for secure seating.

20 - Pressure retention valve

❑ Function 

⇒ page 124

 .

Function of pressure retention valve
From gravity valve (on expansion tank) the pressure retention

valve is open in both directions of flow. -Arrow 1- is the side to

expansion tank.
On the other side it is only open for flow in one direction.

-Arrow 2- is the side to activated charcoal filter.

4.2

Checking fuel system for leaks

Special tools and workshop equipment required
♦ Fuel system tester (so-called smoke tester) -KLI 9210-
♦ Adapter hose -KLI 9210/55-2-
♦ Vehicle diagnosis tester -VAS 5051B- , -VAS 5052- or -VAS

5053-

♦ Hose clamps up to 25 mm -3094-
Test prerequisite:
• A leak has been detected by the fuel system diagnostic pump

-V144- .

• Guided fault finding has been performed with the vehicle di‐

agnosis tester .

Preparation of fuel system tester -KLI 9210- :

Note

The fuel system tester -KLI 9210- may differ in appearance de‐

pending on the version.

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