EVAP/Fuel System, Checking for Leaks
EVAP/Fuel System, Checking for Leaks
=> [ Large Leak in Fuel System Test ]
=> [ EVAP System Function Overview ]
=> [ Leak Detection Pump, Checking Vacuum Supply ]
Special tools, testers and auxiliary items required
• Evaporative Emissions Tester (KLI 9210)
• Adapter hose (KLI 9210/55-1)
• Vehicle Diagnostic Tester
• Hose Clamps up to 25 mm Dia. (3094)
Test Conditions:
• Perform "Guided Fault Finding" using 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 whether 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".
- Using the pressure reducer - J -, adjust the pressure to 10 in. (25 mbar). H2O).
- Set the valve - D - to "Hold".
- The pressure must now be maintained 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 shown.
- 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.
- Start the engine and run at idle speed.
- Select Guided Functions
- Select "Check tank ventilation system for leaks" guided function.
- Start the test.
- While the test runs, observe 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, but the pressure reached does not decrease:
- Turn off the ignition.
- Check the leak detection pump vacuum supply. Refer to => [ Leak Detection Pump, Checking Vacuum Supply ].
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 and the pressure is maintained.
- Set the valve - D - to "Test". Increase the present pressure up to 25 mbar (10 in. H2O).
- Observe the pressure gauge - C - and 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 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 by resetting the valve - D - to "Test".
- Observe the pressure gauge - C - and 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 now no longer falls, replace the EVAP canister purge regulator valve 1.
If the pressure still drops:
- Remove the right rear wheel housing liner.
- Clamp off the hose between the leak detection pump => [ (Item 8) ] and air filter housing => [ (Item 7) Air Filter Housing ] using a hose clamp up to 25 mm dia. (3094) - arrow -
- Reset the valve - D - to "Test".
- Observe the pressure gauge - C - and 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 no longer decreases, replace the leak detection pump.
If the pressure still drops:
- Reset 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 fill tube 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 a ultrasonic measuring device or commercially available leak detection spray.
• Depending on how long the fault finding lasts, the smoke generator button may have 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 the leaking hoses or components.
After completing the work, perform the "Check tank ventilation system for leaks" guided function using the vehicle diagnosis, testing and information system VAS 5051.
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 rear right wheel housing liner.
- Clamp off the hose between the leak detection pump (V144) => [ (Item 8) ] and the air filter housing => [ (Item 7) Air Filter Housing ] using a hose clamp up to 25 mm dia. (3094) - arrow -.
- 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 fuel fill tube 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 a ultrasonic measuring device or commercially available leak detection spray.
• Depending on how long the fault finding lasts, the smoke generator button may have to be pressed again. This ensures there is enough smoke present in the fuel system.
• To check the fuel pump and fuel filter flange, the assembly openings in the vehicle interior must be opened.
- Replace leaking hoses or components.
After completing the work, perform the "Check tank ventilation system for leaks" guided function using the vehicle diagnosis, testing and information system VAS 5051.
EVAP System Function Overview
1 Evaporative Emission (EVAP) Canister
2 Adapter Hose (KLI 9210/55-1) Installed Location
• Used during the fuel system leak test.
3 EVAP Canister Purge Regulator Valve 1 (N80)
4 Vent Line
• To the throttle valve control module (J338)
5 Solenoid Valve
• For the leak detection pump
6 Vacuum Line
• Vehicles through MY 09: to the intake manifold.
• Vehicles from MY 10: to the connection to the vacuum line between the vacuum pump and the brake booster.
7 Air Filter Housing
• For the leak detection pump.
8 Leak Detection Pump (V144)
9 Fuel Tank
10 Cap
Leak Detection Pump, Checking Vacuum Supply
Special tools, testers and auxiliary items required
• Turbocharger Tester (V.A.G 1397 A)
• T Connection (251 201 346)
• 6 mm Diameter Hose
• Leak detection pump (V144) installed location: Under the right rear wheel housing liner.
- Remove the right rear wheel and wheel housing liner.
- Disconnect the vacuum line - 1 - from the leak detection pump.
- Connect the turbocharger tester (V.A.G 1397 A) with the T-piece and 6 mm diameter hose between the vacuum line - 1 - and the leak detection pump - 2 -.
- Turn on measuring range I (absolute pressure measurement).
- Connect the vehicle diagnostic tester and start the engine.
- Select Guided Functions
- Select "Check tank ventilation system for leaks" guided function.
- Start the test.
- While the test is running, observe the display on the turbocharger tester (V.A.G 1397 A).
• The pressure must pulsate and must not rise above 0.700 bar (absolute pressure) during the test.
If the pressure rises above 0.700 bar during the test, the vacuum supply is too low.
- Vehicles through MY 09: make sure that the vacuum line leading to the intake manifold is not bent or plugged.
- Vehicles from MY 10: make sure the vacuum line for the connection to the vacuum line between the vacuum pump and brake booster is not bent or plugged.