Fuel Supply and Ventilation Systems, Checking For Leaks

Checking Fuel Supply And Ventilation Systems For Leaks


NOTE: The following describes areas in the fuel supply and ventilation systems that should be checked for possible leaks. After making necessary repairs, perform leak test again to make sure that all leaks were successfully repaired.


- Switch ignition off.
- Check whether fuel filler cap was completely closed for test.
- Check seal of fuel filler cap for damage. Replace if necessary.

Sedan:
- Remove luggage compartment lining.
- Push forward the right backrest of rear seat, if necessary.

Avant:
- Remove 1/3 backrest, left.
- Remove left side trim of luggage compartment and protective pan.

All vehicles:







- Remove cover (arrows).

Vehicles with all-wheel drive:
- Remove rear seat bench.







- Remove cap for left and right locking flanges (arrows).


NOTE: Observe installation notes for locking flanges for vehicles with front wheel drive and for vehicles with all wheel drive.


All models
- Check whether seals under connection flanges are OK and union nuts are properly tightened. Also check fuel lines connections.
- Visually check all wires and hose connections of fuel supply system and replace loose lines, e.g.:
- Line from EVAP canister to Evaporative Emission (EVAP) canister purge regulator valve (in engine compartment)
- Lines from EVAP canister to Leak Detection Pump (LDP)
- Line from fuel tank to EVAP canister (under cover for EVAP canister)
- Lines from EVAP system (under right-rear wheel housing liner)
- Fuel lines to engine


NOTE: Leaks at lines and components of fuel supply system can sometimes be located using a nonflammable, environmentally sound leak detection spray. For this, initiate leak diagnostic several times in sequence to build pressure in the system. Leaks can be detected via bubbles.


- Visually check components of fuel supply system and EVAP system.
- Fuel tank
- EVAP canister
- Leak detection pump (LDP) -V144-
- Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-


NOTE: Because of shape or function of these components it is not always possible to find leaks by applying spray. It may be necessary to clamp off the relevant component using 3093 hose clamps and initiate leak detection diagnostic. If the leak is no longer detected, the component that was clamped off is faulty. If clamp is placed directly on the diagnostic pump and a leak is still detected, then the diagnostic pump itself is leaking.