Fuel System Leak Test

Fuel System Leak Test

Special tools, testers and auxiliary items required

• Hose Clamps Up to 25 mm Dia. (3094)

• Evaporative Emission Tester (KLI 9210)

• Adapter Hose (KLI 9210/55-1)

Test Conditions:

• The "checking fuel system for leaks" test was performed. Refer to => [ Fuel System, Checking for Leaks ] Fuel System, Checking for Leaks.

• Connect the evaporative emissions tester (KLI 9210) and the adapter hose (KLI 9210/55-1) to the ventilation line.






Test Sequence:

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

- Remove the right rear wheel.

- Remove the right rear wheel housing liner.

- Using a hose clamp up to 25 mm dia. (3094) - arrow -, clamp the connecting hose between the leak detection pump (V144) and the air filter.






- Set valve - D - to "Test".






- Observe the pressure gauge - C - and flow meter - E -. If the flow quantity decreases and pressure increases to 10 in. H2O, then the fuel system is full.

• Depending on the level in the fuel tank, this procedure may take up to 3 minutes.

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

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

If the pressure no longer drops now:

- Replace the Leak Detection Pump (LDP). Refer to => [ ] Service and Repair.

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 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 leaking smoke. Also check the fuel tank filler tube cap.

• 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 have to be pressed again. This ensures there is enough smoke present in the fuel system.

• Remove the cover - 1 - to check the fuel delivery unit flange.






- Replace leaking hoses or components.

- After completing the work, use the vehicle diagnostic tester to run the Check tank ventilation system for leaks guided function.