Fuel Delivery and Air Induction: Testing and Inspection
EVAP/Fuel System, Checking for Leaks
=> [ Large Leak in Fuel System Test ]
Special tools, testers and auxiliary items required
• Evaporative Emissions Tester (KLI 9210)
• Hose Adapter (KLI 9210/55-1)
• Vehicle Diagnostic Tester
• Hose Clamps up to 25 mm Dia. (3094)
Test Conditions:
• Perform the "Guided Fault Finding" the vehicle diagnostic tester.
• The leak detection pump (V144) detected a leak.
Evaporative Emissions Tester (KLI 9210) Preparation:
• Depending on the version, the appearance of the evaporative emissions tester (KLI 9210) may vary.
- Check the evaporative emissions tester (KLI 9210) to determine if there is enough fluid in the smoke generator.
- Set the valve - D - to "Hold".
- Open the nitrogen bottle - H -.
- Connect the measuring hose - G - to the self-test connection - B -.
- Set the valve - D - to "Test".
- Adjust the pressure to 25 mbar (10 in. H2O) using the pressure reducer - J -.
- Set the valve - D - to "Hold".
• The pressure must now be maintained for a minimum of 2 minutes.
If the pressure is not maintained, check the tester.
Fuel System, Checking for Leaks:
- Connect the adapter hose (KLI 9210/55-1) to the ventilation line - A - as illustrated.
- Connect the measuring hose - G - from the evaporative emissions tester (KLI 9210) to the adapter hose (KLI9210/55-1).
- Connect the vehicle diagnostic tester to the vehicle.
The procedure was revised when the electric leak detection pump was introduced.
- Turn the ignition on.
• The engine may be not running.
- Select Guided Functions on the vehicle diagnostic tester.
- Select the "Check tank ventilation system for leaks".
- Start the test.
- Watch the pressure gauge on the evaporative emissions tester (KLI 9210).
• The leak detection pump must pump the fuel system pressure up to at least 18 mbar (7 in. H2O).
The minimum pressure is not reached and the pressure reached decreases immediately:
There is a large leak in the fuel system.
- Turn off the ignition.
- Perform the => [ Large Leak in Fuel System Test ].
The minimum pressure is not reached:
- Turn off the ignition.
• The valve in the leak detection pump is now closed. The pressure is held.
- Set the valve - D - to "Test". Increase the current pressure to 25 mbar (10 in. H2O).
- Watch the pressure gauge - C - and the flow meter - E -.
If the flow quantity decreases and the pressure increases to 25 mbar (10 in. H2O), fuel system is filled.
• Depending on the level in the fuel tank, this procedure may take up to 3 minutes.
- After the pressure has stabilized, set the valve - D - to "Hold".
• After 5 minutes the pressure must not drop below 20 mbar (8 in. H2O).
If the pressure is not maintained for 5 minutes, the leak should be localized as follows:
- First, check the EVAP canister purge regulator valve 1 (N80) for leaks. Clamp off the hose to the EVAP canister purge regulator valve 1 using a hose clamp up to 25 mm dia. (3094) - arrow -.
- Repeat the pressure test. Set the valve - D - to "Test" again.
- Watch the pressure gauge - C - and the flow meter - E -.
If the flow quantity decreases and the pressure increases to 25 mbar (10 in. H2O), the fuel system is filled.
- After the pressure has stabilized, set the valve - D - to "Hold".
If the pressure no longer drops now:
- Replace the EVAP canister purge regulator valve 1.
If the pressure still drops:
- Remove the right rear wheel housing liner.
- Disconnect the line - arrow - from the leak detection pump and seal the opening tight.
- Set the valve - D - to "Test".
- Watch the pressure gauge - C - and the flow meter - E -.
If the flow quantity decreases and the pressure increases to 25 mbar (10 in. H2O), the fuel system is filled.
• Depending on the level in the fuel tank, this procedure may take up to 3 minutes.
- After the pressure has stabilized, set the valve - D - to "Hold".
• After 5 minutes the pressure must not drop below 20 mbar (8 in. H2O).
- If the pressure stops falling, replace the leak detection pump.
If the pressure still drops:
- Set the valve - D - to "Test".
- While fuel system is being filled, press the smoke generator button - I - for approximately one minute.
The fuel system is now under pressure and filled with smoke.
- Check all fuel system lines and hoses for escaping smoke. Also check the fuel cap.
• Locations, refer to => [ EVAP System Overview ] EVAP System Overview.
• Shine a strong light on the components and hoses. The smoke will be more visible.
• To check for leaks at accessible locations, also use a ultrasonic measuring device or commercially available leak detection spray.
• Depending on how long the fault finding lasts, the smoke generator button may need to be pressed again. This ensures there is enough smoke present in the fuel system.
• Remove the cover - 1 - to check the fuel delivery unit flange.
- Replace any leaking hoses or components.
After completing the work, perform the "Check tank ventilation system for leaks" guided function using the vehicle diagnostic tester.
Large Leak in Fuel System Test
Test Conditions:
• The evaporative emissions tester (KLI 9210) and the adapter hose (KLI 9210/55-1) are connected to the vehicle. Refer to => [ EVAP/Fuel System, Checking for Leaks ] EVAP/Fuel System, Checking for Leaks.
- Connect the evaporative emissions tester (KLI 9210) to the vehicles battery.
- Remove the right rear wheel housing liner.
- Disconnect the line - arrow - from the leak detection pump (V144) and seal the opening in the pump tight.
- Set the valve - D - to "Test".
- While the fuel system is being filled, press the smoke generator button - I - for approximately one minute.
The fuel system is now under pressure and filled with smoke.
- Check all fuel system lines and hoses for escaping smoke. Also check the fuel cap.
• Locations, refer to => [ EVAP System Overview ] EVAP System Overview.
• Shine a strong light on the components and hoses. The smoke will be more visible.
• To check for leaks at accessible locations, also use a ultrasonic measuring device or commercially available leak detection spray.
• Depending on how long the fault finding lasts, the smoke generator button may need to be pressed again. This ensures there is enough smoke present in the fuel system.
• Remove the cover - 1 - to check the fuel delivery unit flange.
- Replace any leaking hoses or components.
After completing the work, perform the "Check tank ventilation system for leaks" guided function using the vehicle diagnostic tester.