FUEL SYSTEM, CHECKING FOR LEAKS, VEHICLES WITH Fuel Tank Leak Detection Module -GX36-

Special tools and workshop equipment required 

• Smoke Tester: VAS523005 
• Connector: VAS523005/4 
• Connection Set: VAS523005/5  , : VAS523005/6  or : VAS523005/7  (depending on the diameter of the breather line)
• Plugs: VAS523005/8 
• Protective eyewear (yellow)
• Smoke Tester: VAS523005  operating instructions

Connector Coupling	Color Coding on Connector Coupling
Fuel supply	Black
Fuel Return Line	Blue
Bleeder	White or beige

Test Conditions:

• Guided Fault Finding was performed using the Vehicle Diagnostic Tester.
• The Leak Detection Pump -V144- detected a leak.

Preparing the Smoke Tester: VAS523005 

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-- Check the water separator -A- on the smoke tester. Drain the water separator if necessary.

-- Connect the pressure hose to the connection -B-.

-- Use the dipstick -D- to check if there is enough fluid in the Smoke Tester.

-- Connect the power supply for the Smoke Tester -C- to the jump start point on the vehicle.

-- Remove the center underbody trim panel. Refer to COMPONENT LOCATION OVERVIEW - UNDERBODY TRIM PANELS .

-- Disconnect the breather line on the underbody -arrow- and check which Connecting Cable Set should be used.

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Check the Smoke Tester and Connection Set for Leaks:

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-- Connecting the Connector -A- and Connection Set -B- as shown.

-- Open the shut-off valve -C-.

-- Connect the measuring hose on the smoke tester to the hose -D-.

-- Set the valve -A- to "TEST".

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-- Switch on the Smoke Tester -B-. The Connection Set will then be filled with smoke.

-- Watch the pressure gauge -C- and the flow meter -D-.

If the pressure rises to 35 mbar and the ball in the flow meter sinks to >>zero<<, then there are no leaks in the Smoke Tester and the Connection Set and they can be used.

-- Switch off the Smoke Tester.

Check the EVAP Canister Purge Regulator Valve 1 -N80- for Leaks:

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-- Connect the Connection Set between the breather lines -1 and 2- on the vehicle as shown.

-- Connect the measuring hose on the Smoke Tester to the Connector -3-.

-- Close the shut-off valve -A- (line to the EVAP canister).

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-- Set the valve -A- to "TEST".

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-- Switch on the Smoke Tester. The hose to the Solenoid Valve -- will then be filled with smoke.

If the pressure rises to 35 mbar (0.5 psi) and the ball in the flow meter sinks to >>zero<<, then the EVAP Canister Purge Regulator Valve 1 - N80- has no leaks and is OK.

-- Switch off the Smoke Tester.

Checking the EVAP Canister, Fuel Tank, and Lines for Leaks:

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-- Open the shut-off valve -A- (line to the EVAP canister).

-- Remove right rear wheel housing liner.

-- Remove the air filter for the Leak Detection Pump -V144-. Refer to AIR FILTER FOR Fuel Tank Leak Detection Module .

-- Fill the fuel system with smoke by setting the valve -A- to "SMOKE" and switching on the Smoke Tester.

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-- Allow the fuel system to fill with smoke until smoke escapes from the connection -A- on the Leak Detection Pump --.

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-- If smoke escapes, seal the connection -A- with a Plugs: VAS523005/8  .

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-- Set the valve -A- to "TEST" and continue filling the fuel system.

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-- Watch the pressure gauge -C- and the flow meter -D-.

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If the pressure rises to 35 mbar (0.5 psi) and the ball in the flow meter sinks below the >>0.25 mm mark<< -arrow-, then the fuel system is filled.

-- Once the flow meter has stabilized, switch the Smoke Tester off and check the pressure gauge.

• The pressure must not drop below 30 mbar (0.43 psi) after five minutes.

If the Pressure Drops or If No Pressure Develops, Then Locate the Leak as Follows:

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-- Set the valve -A- to "SMOKE" and fill the fuel system with smoke.

-- Check all the lines, hoses and the fuel filler cap for escaping smoke.

-- Shine a flashlight on all components and hoses, because the smoke is more visible in white light.

-- Use the laser to narrow down the location of the leak. The laser beam will >>light up<< in the smoke and be visible.

-- The smoke contains a contrast agent. The contrast agent will be visible at the location of the leak under ultraviolet light.

-- The installation opening inside the passenger compartment must be opened 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 with the Vehicle Diagnostic Tester.