Fuel System, Checking For Leaks: Notes

Special Tools And Workshop Equipment Required 

• Hose Clamps Up to 25 mm Dia. 3094
• Vehicle Diagnostic Tester
• Evaporative Emission Tester KLI 9210
• Adapter Hose KLI 9210/55-1

Test Conditions: 

• The "Guide Fault Finding" was performed using the vehicle diagnostic tester.
• A leak in the leak detection pump -V144- was detected.

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 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 valve -D- to "Test".

-- Using the pressure reducer -J-, adjust the pressure to 10 in. H2O (25 mbar).

-- Set 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.

Test Sequence: 

-- Read the safety precautions before starting. Refer to SAFETY PRECAUTIONS .

-- Pay attention to the rules of cleanliness. Refer to CLEAN WORKING CONDITIONS .

-- Connect the adapter hose KLI 9210/55-1 to the ventilation lines -A- as illustrated.

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

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the vehicle diagnostic tester -1- as follows:

Fig 4: Connecting Evaporative Emissions Tester To Vehicle

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the diagnostic cable -2- to the Data Link Connector (DLC) in the drivers foot well.

-- Start the engine and run at idle speed.

-- Select Guided Functions  on the vehicle diagnostic tester.

-- 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 (LDP) must pump the fuel system up to a min. 18 mbar (7 in. Inflate H2O (18 mbar).

The minimum pressure is not reached, but the pressure reached does not decrease: 

-- Turn off the ignition.

-- Perform a pressure retention test. Refer to Pressure Retention Test .

If no decrease in pressure is observed: 

-- Check the vacuum supply for the LDP. Refer to Leak Detection Pump -V144- VACUUM SUPPLY, CHECKING .

The minimum pressure is not reached and the pressure reached decreases immediately: 

-- Using a hose clamp up to 25 mm dia. 3094 -arrow-, clamp off the hose to the EVAP canister purge regulator valve 1 -N80-.

Fig 5: Clamping Off Hose To EVAP Canister Purge Regulator Valve 1 -N80- Using Hose Clamps Up To 25 Mm Dia. 3094

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Repeat the test.

If the minimum pressure is not reached: 

-- Replace the EVAP canister purge regulator valve 1.

The minimum pressure is not reached again and 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 .

If the minimum value is obtained: 

-- Turn off the ignition.

The valve in the LDP is now closed and the pressure is maintained.

-- Observe the pressure gauge:

If the pressure does not drop: 

-- Perform a pressure retention test to locate any possible pinhole leaks. Refer to Pressure Retention Test .

If the pressure drops:

-- Using a hose clamp up to 25 mm dia. 3094 -arrow-, clamp off the hose to the EVAP canister purge regulator valve 1.

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

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

If the pressure no longer drops now: 

-- Replace the EVAP canister purge regulator valve 1.

If the pressure still drops: 

-- There is a leak in the fuel system, perform the "fuel system leak test". Refer to FUEL SYSTEM LEAK TEST .