Fuel System Leak Test

WARNING: This page is about a different car, the 2008 Volkswagen R32. However, it is still accessible from the selected car via links, so may be relevant.

Test Conditions

Procedure for "Checking fuel system for leaks" was performed. Refer to FUEL/EVAP SYSTEM, CHECKING FOR LEAKS .
KLI 9210 with KLI 9210/55-1 still connected to the vehicle.

Fig 1: Identifying Measuring Hose On Evaporative Emissions Tester Connected KLI 9210 To Adapter Hose KLI 9210/55-1
Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the KLI 9210 to the vehicle's battery.

-- Remove the right rear wheel housing liner. Refer to FRONT WHEEL HOUSING LINER .

-- Clamp off the hose between the Leak Detection Pump (LDP) and air filter -arrow-.

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

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

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

Fig 3: Identifying Evaporative Emission (EVAP) Canister Purge Regulator Components

Courtesy of VOLKSWAGEN GROUP OF AMERICA, 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 H2O (20 mbar) drop.

-- If the pressure no longer decreases, replace the LDP.

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 the fuel tank filler tube 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 ultrasonic measuring device or commercially available leak detection spray.

Depending on how long the fault finding lasts, the smoke generator button may have to be pressed again. This ensures there is enough smoke present in the fuel system.

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

-- Replace the leaking hoses or components.

After completing the work, perform the "Check tank ventilation system for leaks".