Fuel/EVAP System, Checking For Leaks

Fuel/EVAP System, Checking For Leaks (Passat)

Special tools, testers and auxiliary items required
- Fuel system tester (smoke tester) KLI 9210
- Hose adapter KLI 9210/55-1
- Vehicle diagnosis, testing and information system VAS 5051B, VAS 5052 or VAS 5053
- Hose clamps up to 25 mm diameter 3094

Test Conditions
- A leak was detected by Leak Detection Pump (LDP) V144.
- Guided fault finding was performed with vehicle diagnosis, testing and information system.

Evaporative Emissions Tester KLI 9210 Preparation

NOTE: 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 the 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 a pressure reducer - J -, adjust the pressure to 10 in. H2O (25 mbar).
- Set valve - D - to "Hold".
- The pressure must now be maintained min. 2 minutes. If the pressure is not maintained, check the tester.

Fuel System, Checking for leaks







- Connect adapter hose KLI 9210/55-1 to ventilation line - A - as shown.







- Connect measuring hose - G - on evaporative emissions tester KLI 9210 to adapter hose KLI 9210/55-1.
- Set valve - D - to "Hold".







- Connect evaporative emissions tester to vehicle.
- Start engine and run at idle speed.
- Select Guided Functions operating mode on evaporative emissions tester.
- Select "Check tank ventilation system for leaks" guided function.
- Activate test.
- While the test runs, observe pressure gauge on evaporative emissions tester KLI 9210.
- The Leak Detection Pump (LDP) V144 must pump the fuel system pressure up to at least 7 in. H2O (18 mbar).

The minimum pressure is not reached, but the pressure reached does not decrease:
- Switch ignition off and perform pressure retention test. If no decrease in pressure is observed: Check the Leak Detection Pump (LDP) V144 vacuum supply.

The minimum pressure is not reached and the pressure reached decreases immediately:







- Clamp off hose to evaporative emission (EVAP) canister purge regulator valve N80 with hose clamp.
- Repeat the test. If minimum pressure is not reached: Replace evaporative emission (EVAP) canister purge solenoid valve 1 N80.

The minimum pressure is not reached again and the pressure reached decreases immediately:
- Leak in fuel system, perform "leak test in fuel system".

If the minimum pressure is reached, switch ignition off.
The valve in the Leak Detection Pump (LDP) V144 is now closed and the pressure is maintained.
- Observe pressure gauge:

If the pressure does not decrease, perform a pressure retention test to locate any possible pinhole leaks.







If the pressure decreased, clamp off hose to evaporative emission (EVAP) canister purge regulator valve N80 with a hose clamp.
- If pressure now no longer falls, replace evaporative emission (EVAP) canister purge regulator valve N80.

If the pressure still decreases, perform "leak test in fuel system".

Pressure Retention Test







- Set valve - D - to "Test". Increase the pressure up to 10 in. H2O (25 mbar).
- Observe the pressure gauge - C - and flow meter - E -. The fuel system is filled if the flow quantity decreases and the pressure increases to 10 in. H2O (25 mbar).

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

- After the pressure has stabilized, set valve - D - to "Hold".
- After 5 minutes the pressure must not drop below H2O (20 mbar) drop.

If the pressure is not maintained for 5 minutes, the leak should be localized as follows







- 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.







- Repeat pressure test by resetting valve - D - to "Test".
- Observe pressure gauge and flow meter. The fuel system is filled if the flow quantity decreases and the pressure increases to 10 in. H2O (25 mbar).
- After the pressure has stabilized, set valve - D - to "Hold".
- If pressure now no longer falls, replace evaporative emission (EVAP) canister purge regulator valve N80.

If the pressure still decreases, perform "leak test in fuel system" Fuel System Leak Test.

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