Fuel/EVAP System, Checking For Leaks: Notes

Special tools and workshop equipment required 

• Hose clamps up to 25 mm diameter 3094
• Fuel system tester (smoke tester) KLI 9210
• Hose adapterKLI 9210/55-1
• Vehicle diagnosis, testing and information system VAS 5051B, VAS 5052 or VAS 5053

Test Conditions 

• A leak was detected by the Leak Detection Pump (LDP).
• Guided fault finding was performed with the vehicle diagnosis, testing and information system.

KLI 9210 Preparation 

-- Check the KLI 9210 to see if 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. H2O (25 mbar).

-- 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 

Fig 2: Identifying Quick-Release Coupling Between Ventilation Line And Adapter

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the KLI 9210/55-1 to the ventilation line -A- as shown.

-- Connect the measuring hose -G- from the KLI 9210 to the KLI 9210/55-1.

Fig 3: Identifying Measuring Hose On Evaporative Emissions Tester Connected KLI 9210 To Adapter Hose KLI 9210/55-1

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

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

-- Connect the KLI 9210 to the vehicle battery.

-- Connect the vehicle diagnosis, testing and information system to the vehicle as follows:

Fig 4: Identifying Evaporative Emissions Tester Connected To Vehicle

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the diagnostic cable -2- connector to the Data Link Connector (DLC) in the driver's footwell.

-- Start the engine and run at idle speed.

-- Select the Guided Functions  operating mode on the vehicle diagnosis, testing and information system.

-- Select the "Check tank ventilation system for leaks" guided function.

-- Activate the test.

-- While the test runs, observe the pressure gauge on the KLI 9210.

• The LDP must pump the fuel system pressure up to at least 7 in. H2O (18 mbar).

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

-- Switch the ignition off and perform pressure retention test. Refer to PRESSURE RETENTION TEST . If no decrease in pressure is observed: Check the LDP vacuum supply. Refer to LEAK DETECTION PUMP, CHECKING VACUUM SUPPLY .

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

-- Clamp off the hose to the Evaporative Emission (EVAP) canister purge regulator valve using the 3094.

Fig 5: Identifying Hose To Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 Clamped Off With Hose Clamp

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Repeat the test. If the minimum pressure is not reached: Replace the EVAP canister purge solenoid valve 1.

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

-- Leak in the fuel system, perform the fuel system leak test. Refer to FUEL SYSTEM LEAK TEST .

If the minimum pressure is reached, switch the ignition off.

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

-- Observe the pressure gauge:

If the pressure does not decrease, perform a pressure retention test to locate any possible pinhole leaks. Refer to PRESSURE RETENTION TEST .

If the pressure decreased, clamp off the hose to EVAP canister purge regulator valve using the 3094.

Fig 6: Identifying Hose To Evaporative Emission (EVAP) Canister Purge Regulator Valve N80 Clamped Off With Hose Clamp

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- If pressure now no longer falls, replace the EVAP canister purge regulator valve.

If the pressure still decreases, perform the fuel system leak test. Refer to FUEL SYSTEM LEAK TEST .