EVAP/Fuel System, Checking For Leaks: Notes

Special tools and workshop equipment 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:

-- Check the evaporative emissions tester KLI 9210 to determine whether there is enough fluid in the smoke generator.

-- Set the valve -D- to "Hold".

Fig 1: Identifying Evaporative Emission (EVAP) Canister Purge Regulator Components

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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.

Fig 2: Connecting Adapter For Evaporative Emission Tester KLI 9210/55-1 To Ventilation Line

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-- Connect the measuring hose -G- from the evaporative emissions tester KLI 9210 to the adapter hose KLI9210/55-1.

Fig 3: Connecting Measuring Hose From Evaporative Emissions Tester KLI 9210 To Adapter For Evaporative Emission Tester KLI 9210/55-1

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-- Connect the vehicle diagnostic tester to the vehicle.

Fig 4: Connecting Evaporative Emissions Tester To Vehicle

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-- 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.

-- Set the valve -D- to "Test". Increase the present pressure up to 25 mbar (10 in. H2O).

Fig 5: Identifying Evaporative Emission (EVAP) Canister Purge Regulator Components

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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".

• 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-.

Fig 6: Clamping Off Hose To EVAP Canister Purge Regulator Valve 1 -N80- Using Hose Clamps Up To 25 Mm Dia. 3094

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-- Repeat the pressure test by resetting the valve -D- to "Test".

Fig 7: Identifying Evaporative Emission (EVAP) Canister Purge Regulator Components

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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 and air filter housing using a hose clamp up to 25 mm dia.3094 -arrow-.

Fig 8: Clamping Off Hose Between Leak Detection Pump (LDP) V144 And Air Filter

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-- Reset the valve -D- to "Test".

Fig 9: Identifying Evaporative Emission (EVAP) Canister Purge Regulator Components

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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".

• 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.

NOTE:

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.

Fig 10: Removing Cover From Fuel Delivery Unit

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-- 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.