Fuel System Leak Test

WARNING: This page is about a different car, the 2009 Volkswagen GTI and 2008 Volkswagen GTI. However, it is still accessible from the selected car via links, so may be relevant.

Test Conditions

The "Fuel System, Checking for Leaks" procedure was performed. If not, refer to FUEL SYSTEM, CHECKING FOR LEAKS .
The evaporative emissions tester -KLI 9210- and the adapter for evaporative emission tester KLI 9210/55-1 are still connected to the vehicle

Fig 1: Identifying Measuring Hose From Evaporative Emissions Tester KLI 9210 Connected To Adapter Hose KLI 9210/55-1
Courtesy of VOLKSWAGEN UNITED STATES, INC.

-- Connect the evaporative emissions tester -KLI 9210- to the vehicles battery.

-- Remove the right rear wheel housing liner.

-- Clamp off the hose between the leak detection pump -V144- and the air filter using a hose clamp up to 25 mm dia. -3094- -arrow-.

Fig 2: Identifying Hose Clamp -3094-, Leak Detection Pump (LDP) V144 And Air Filter (Eos)

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Fig 3: Identifying Hose Clamp -3094-, Leak Detection Pump (LDP) V144 And Air Filter

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Fig 4: Identifying Evaporative Emission (EVAP) Canister Purge Regulator Components

Courtesy of VOLKSWAGEN UNITED STATES, INC.

-- Observe the pressure gauge -C- and flow meter -E-. The fuel system is filled if the flow quantity decreases and the pressure increases to 10 in. H2O (25 mbar).

-- After the pressure has stabilized, set the valve -D- to "Hold".

After 5 minutes the pressure must not drop below 8 in. H2O (20 mbar).

-- If the pressure no longer decreases, replace the leak detection pump.

If the pressure is not maintained for a minimum of 5 minutes or if no pressure is built up, localize the leak as follows:

-- Fill the fuel system with smoke by setting 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 fuel tank sealing 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 need to be pressed again. This ensures there is enough smoke present in the fuel system.

To check the fuel pump and fuel filter flange, the assembly openings in the vehicle interior must be opened.

-- Replace any leaking hoses or components.

After completing the work, perform the "Check tank ventilation system for leaks" guided function using the vehicle diagnostic tester.