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Home >> Volkswagen >> 2005 >> Touareg (7LA) V8-4.2L (BHX) >> Repair and Diagnosis >> Powertrain Management >> Emission Control Systems >> Evaporative Emissions System >> Testing and Inspection >> EVAP System, Checking For Leaks >> Fuel Supply

Fuel Supply






EVAP System, Checking for Leaks

Special tools, testers and auxiliary items required

• Fuel system tester (smoke tester) (KLI 9210)

• Hose adapter (KLI 9210/55-2)

• Vehicle Diagnosis, Testing and Info. System (VAS 5051B), (VAS 5052) or (VAS 5053)

• Hose Clamps Up to 25 mm dia. (3094)





Test conditions:

• A leak was detected by Leak Detection Pump (LDP) (V144).

• Guided Fault Finding was performed with Vehicle Diagnosis, Testing and Info. System.

Evaporative Emissions Tester (KLI 9210) preparation:

• Depending on the version, the appearance of the Evaporative Emissions Tester (KLI 9210) may vary.

- Check on Evaporative Emissions Tester (KLI 9210) whether there is enough fluid in smoke generator.

- Set valve - D - to "Hold".





- Open nitrogen bottle - H -.

- Connect measuring hose - G - on self-test connection - B -.

- Set valve - D - to "Test".

- Using pressure reducer - J -, adjust pressure to 25 mbar (10 in. H2O).

- Set valve - D - to "Hold".

- The pressure must now be maintained min. 2 minutes. If pressure is not maintained, check tester.

Fuel system, checking for leaks:

- Pull rear engine cover off - arrows -.





- Disconnect breather line - arrow - to evaporative emission (EVAP) canister purge regulator valve (N80) in engine compartment.





- Connect Adapter Hose (KLI 9210/55-2) as shown between Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80) and ventilation line - A -.





- Connect measuring hose - G - on Evaporative Emissions Tester (KLI 9210) to Adapter Hose (KLI 9210/55-2).

- Connect Evaporative Emissions Tester (KLI 9210) to vehicle battery.

- Connect evaporative emissions tester to vehicle.





- Start engine and run at idle speed.

- Select OBD operating mode on evaporative emissions tester.

- Now select diagnostic mode 8 "Tank leak test".

- Mark "Tank leak test" entry and press right arrow button > to activate test.

• When diagnostic mode 8 "Tank leak test" is activated, leak detection pump and Evaporative Emission (EVAP) Canister Purge Solenoid Valve 2 (N115) are closed for a maximum of 1000 seconds. The Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80) is not activated. The entire system is now closed.

• If the engine control module stops the test, it can be reactivated by stopping the engine and restarting.

- Set valve - D - to "Test". The fuel system is now filled with nitrogen.





- Observe pressure gauge - C - and flow meter - E -. If the flow quantity decreases and pressure climbs to 25 mbar (10 in. H2O), the fuel system is full.

• Depending on level in the fuel tank, this procedure may take up to 3 minutes.

- After pressure has stabilized, set valve - D - to " Hold".

• The pressure must not drop below 20 mbar (8 in. H2O) after 5 minutes.

If no pressure decrease can be determined, end diagnostic mode 8 and check Leak Detection Pump (LDP) (V144) pressure buildup --> [ Leak Detection Pump Pressure, Checking ] Leak Detection Pump Pressure, Checking.

If pressure does not build up or if positive pressure is not maintained for at least 5 minutes, locate leak as follows:

Allow engine to continue running at idle with diagnostic mode 8 activated.

- First check Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80) for leaks. Clamp off hose to Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80) with hose clamp - arrow -.





- Repeat pressure test by resetting valve - D - to " Test".





- Observe pressure gauge and flow meter. If flow quantity decreases and pressure climbs to 25 mbar (10 in. H2O), the fuel system is full.

- After pressure has stabilized, set valve - D - to " Hold".

- If pressure now no longer falls, replace Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80).

If pressure still drops:

- Reset valve - D - to "Test".

- While fuel system is being filled, press smoke generator button - I - for approx. one minute.

The fuel system is now under pressure and filled with smoke.

- Check all visible fuel system lines and hoses for escaping smoke. Also check fuel tank sealing cap.

• Illuminate components and hoses with a strong flood light, the smoke will be more visible.

• To check for leaks at accessible locations, also use ultrasonic measuring device or commercially available leak detection spray.

• Depending on how long fault finding lasts, smoke generator button may have to be pressed again. This ensures there is enough smoke present in the fuel system.

If no malfunctions are detected:

- Remove right rear wheel housing liner.

If smoke comes out of air filter:

- Clamp off hose between Evaporative Emission (EVAP) Canister Purge Solenoid Valve 2 (N115) and air filter - arrow -.





- Observe air filter. If no smoke comes out of it now, the Evaporative Emission (EVAP) Canister Purge Solenoid Valve 2 (N115) leaks. Replace Evaporative Emission (EVAP) Canister Purge Solenoid Valve 2 (N115).

If smoke still comes out of air filter:

- Clamp off hose between Leak Detection Pump (LDP) (V144) and air filter - arrow -.





- Observe air filter. If no smoke comes out of it now, shut-off valve in Leak Detection Pump (LDP) (V144) leaks. Replace Leak Detection Pump (LDP) (V144).

If no smoke comes out of air filter:

- Check all fuel system components and hoses for escaping smoke.

To check fuel pump and fuel filter flange, assembly opening in vehicle interior must be opened.

- Replace leaking hoses or components.

After completing work, perform "Check tank ventilation system for leaks" guided function using.
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