Fuel Delivery and Air Induction: Testing and Inspection
Fuel System, Checking for Leaks
=> [ Fuel System Leak Test ]
Special tools, testers and auxiliary items required
• Evaporative Emission Tester (KLI 9210)
• Adapter for Evap. Tester (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.
Procedure
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 make sure 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 25 mbar (10 in. H2O).
- 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 for evap. tester (KLI 9210/55-1) to the vent lines - A - "with white marks" as illustrated.
- Connect the measuring hose - G - from the evaporative emissions tester (KLI 9210) to the adapter for evap. tester (KLI9210/55-1).
- Connect the vehicle diagnostic tester cable - 2 - to the vehicle.
The procedure was revised when the electric leak detection pump was introduced.
- Turn on the ignition.
• The engine may be not running.
- Select the type of operation for 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 25 mbar (25.40 cm. H2O).
The minimum pressure is not reached and the pressure reached decreases immediately:
- Clamp off the hose to the EVAP canister purge regulator valve 1 (N80) using a hose clamps up to 25 mm dia. (3094) - arrow -.
- Repeat the test. If the minimum pressure is not reached: Replace the EVAP canister purge regulator valve 1 (N80).
The minimum pressure is not reached again or the pressure reached decreases immediately:
- There is a leak in the fuel system: Perform the "Fuel System Leak Test". Refer to => [ Fuel System Leak Test ].
Fuel System Leak Test
Test Conditions:
• The "Fuel System, Checking for Leaks" was performed.
• The evaporative emissions tester (KLI 9210) and the adapter for evap. tester (KLI 9210/55-1) are still connected to the vehicle.
- Connect the evaporative emissions tester (KLI 9210) to the vehicles battery.
- Remove the right rear wheel housing liner.
- Disconnect the air filter housing hose - arrow - from the leak detection pump (V144).
- Plug the connection on the leak detection pump with a plug - A -.
- Set the valve - D - to "Test". The fuel system is now filled.
- Watch the pressure gauge - C - and the flow meter - E -. If the flow quantity decreases and pressure increases to 10 in. H2O, then the fuel system is full.
- After the pressure has stabilized, set the valve - D - to "Hold".
• After 5 minutes the pressure must not drop below 8 in. H2O (20 mbar).
If the pressure drops or if no pressure develops, then locate the leak as follows:
- Set the valve - D - to "Test" and fill the system with smoke.
- 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 the lines, hoses and the fuel cap for escaping smoke.
• Illuminate components and hoses with a strong flood light, the smoke will be more visible.
• An ultrasonic sensor tester or commercially available leak spray can also be used to locate leaks.
• 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.
• It is necessary to open the opening inside the passenger compartment to check the flange on the fuel pump and fuel filter.
- 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.