Fuel System, Checking For Leaks
Fuel System, Checking For Leaks (Passat And Tiguan)
Special tools, testers and auxiliary items required
- Fuel system tester (smoke tester) KLI 9210
- Hose adapter KLI 9210/55-1
- Vehicle Diagnosis, Testing and Info. 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.
- Guided Fault Finding was performed.
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.
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 test runs, observe pressure gauge on evaporative emissions tester KLI 9210.
- The leak detection pump 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 vacuum supply. Leak Detection Pump, Checking Vacuum Supply
The minimum pressure is not reached and the pressure reached decreases immediately:
- Clamp off hose to EVAP canister purge regulator valve with hose clamp.
- Repeat test. If minimum pressure is not reached, replace the EVAP canister purge regulator valve.
The minimum pressure is not reached again and the pressure reached decreases immediately:
- Fuel system leak.
If minimum pressure is reached, switch ignition OFF.
The valve in the leak detection pump is now closed and the pressure is maintained.
- Observe pressure gauge.
If pressure does not decrease, perform a pressure retention test to locate any possible pinhole leaks.
If pressure decreased, clamp off hose to EVAP canister purge regulator valve with a hose clamp.
- If pressure now no longer falls, replace EVAP canister purge regulator valve.
If pressure still decreases. Fuel System Leak Test
Pressure Retention Test
- Set valve - D - to "Test". Increase the pressure up to 10 in. H2O (25 mbar).
- Observe 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 8 in. H2O (20 mbar) drop.
If pressure is not maintained for 5 minutes, the leak should be localized as follows:
- First check EVAP canister purge regulator valve for leaks. Clamp off hose to EVAP canister purge regulator valve 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 the EVAP canister purge regulator valve.
If pressure still decreases. Fuel System Leak Test
After completing the work, perform "Check Tank Ventilation System For Leaks" guided function.