Performing Diagnostic Leak Test

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Diagnostic Leak Test Occurs In "Guided Fault Finding".

Checking Fuel Supply And Tank Ventilation Systems For Leaks

NOTE:

The Following Describes Individual Areas In The Fuel Supply And Ventilation Systems Where Leaks Are Possible. After Repairing A Possible Leak, Perform A Leak Test To Ensure That Leak Was Successfully Repaired.

-- Switch Off Ignition.

Fig 1: Identifying Fuel Filler Cap (Fuel Cap)

Courtesy of AUDI OF AMERICA, LLC

-- Check If Fuel Tank Locking Cap -arrow- Was Closed Completely During The Test.

-- Check Whether Seal Of Fuel Filler Cap Was Damaged Or Crimped. Replace If Necessary.

-- Remove Rear Bench Seat. Refer To SEAT BENCH/SINGLE SEAT, REMOVING AND INSTALLING .

Fig 2: Identifying Cover Bolts For Locking Flange

Courtesy of AUDI OF AMERICA, LLC

-- Remove locking flange cover -arrows-.

NOTE:

Observe installation notes for locking flanges INSTALLING .

-- Check if sealing rings under locking flanges are OK or if locking rings on locking flange are tightened correctly on the fuel tank. Also check fuel line connections.

-- Visually check all lines and hose connections on fuel system and replace leaking lines such as:

Line from EVAP canister to Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
Lines from EVAP canister to Leak Detection Pump (LDP) -V144-.
Line from fuel tank to EVAP canister (below heat shield for EVAP canister).
Lines for tank ventilation (beneath right rear wheel housing liner).
Fuel lines to engine.

NOTE:

Leaks at lines and components of tank system can sometimes be located using a non-flammable, environmentally compliant leak detection spray. For this, initiate leak diagnostic several times in sequence to build up pressure in the system. At leaking areas, bubbles will form.

-- Perform a visual inspection on fuel system components and tank ventilation system:

Fuel Tank
EVAP canister
Leak detection pump (LDP) -V144-
Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-

NOTE:

Due to the form or function of the components, leaking areas may not always be localized by spraying on leak detection spray. It may be necessary to clamp off the relevant component using Hose Clamps Up to 25 mm Dia.:3094 and initiate tank leak detection diagnostic. If the leak is no longer indicated, the component that was clamped off is faulty. If clamped off directly at the leak detection pump and a leak is still indicated, the leak detection pump itself is leaking.