Fuel System, Checking For Leaks
Versions with fuel tank leak detection
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)
Connector Coupling Allocation
The connector couplings for fuel, vacuum and bleeder lines are color-coded. There is either a colored dot on the connector coupling, or the release button has the corresponding color. Refer to Color Coding .
Test Conditions:
- "Guided Fault Finding" was performed using the Vehicle Diagnostic Tester.
- A leak must have been detected by the Fuel Tank Leak Detection Module -GX36-.
TIP:
The "Small leak" DTC means that the total of all leaks is equal to a leak with a diameter greater than 1.0 mm.
Smoke Tester: VAS523005 application. Refer to Operating Instructions for Smoke Tester VAS523005
Preparing the Smoke Tester: VAS523005
-- Check the water separator -A- on the smoke tester. If necessary, drain the water separator.
-- 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 -C- for the smoke tester to the jump start points in the vehicle.
-- Remove the right rear underbody trim panel. Refer to OVERVIEW - UNDERBODY TRIM PANELS .
-- Disconnect the breather line -arrow- on the underbody and check which connecting cable set should be used. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, DISCONNECTING .
Check the Smoke Tester and Connection Set for Leaks:
-- Connect the connector -A- and connection set -B- as shown.
-- Open the shut-off valve -C-.
-- Connect the measuring hose from the smoke tester to the hose -D-.
-- Set the valve -A- to "TEST".
-- Switch on the : VAS523005 -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 (0.5 psi) 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:
-- Connect the connection set between the breather lines -1 and 2- on the vehicle as shown.
-- Connect the measuring hose from the smoke tester to the connecting piece -3-.
-- Close the shut-off valve -A- (line to the EVAP canister) in direction of -arrow-.
-- Set the valve -A- to "TEST".
-- Switch on the Smoke Tester: VAS523005 -B-.
- The hose to the EVAP Canister Purge Regulator Valve 1 -N80- will now be filled with smoke.
-- Watch the pressure gauge -C- and the flow meter -D-.
- 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:
-- Open the shut-off valve -A- (line to the EVAP canister) in direction of -arrow-.
-- Remove the right rear wheel housing liner. Refer to OVERVIEW - REAR WHEEL HOUSING LINER .
-- Disconnect the vent hose -2- from the Fuel Tank Leak Detection Module -GX36- by pressing the catches.
-- Fill the fuel system with smoke by setting valve -A- to "SMOKE" -arrow- and switching on the Smoke Tester: VAS523005 .
-- Allow the fuel system to fill with smoke until smoke escapes from the connection -arrow- on the detection pump -1-.
-- Once smoke escapes, seal the connection with a Plug: VAS523005/8 .
-- Set the valve -A- to "TEST" -arrow- and continue filling the fuel system.
-- Watch the pressure gauge -C- and the flow meter -D-.
- 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.
TIP:
- If a sporadic fault is detected, move the lines, hoses, and caps. If the flow meter indicates a change when a component is moved, check that component.
- Depending on the fuel level in the fuel tank, it may take up to five minutes to fill with smoke.
- The : VAS523005 has an automatic shut-off system. The smoke tester may need to be switched on again if it shuts off.
-- 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 No Pressure Builds, Locate the Leak as Follows:
-- Set the valve -A- to "SMOKE" -arrow- 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. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .
-- 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.
Tightening Specifications
- Refer to OVERVIEW - UNDERBODY TRIM PANELS .
- Refer to OVERVIEW - REAR WHEEL HOUSING LINER .