EVAP System, Testing

-- Plug or clamp LDP inlet (filter side) using Hose Clamps Up to 25 mm Dia.: VAS3094 or equivalent.

-- Attach fuel cap adapter to filler neck (-arrow-) and test hose to adapter.

Fig 1: Attaching Fuel Cap Adapter To Filler Neck (-Arrow-) And Test Hose To Adapter

Courtesy of AUDI OF AMERICA, LLC

-- Set control valve -2- from "Hold" to "Test".

Fig 2: Connect Vehicle Interface Hose To Self-Test Port

Courtesy of AUDI OF AMERICA, LLC

-- Increase the current pressure until it reaches 10 in. (25 mbar) H₂ O.

-- Monitor the pressure gauge -3- and the flow meter -4-. Allow the flow rate to decrease. If pressure builds to 10 in. (25 mbar) H₂ O, the fuel system is full.

NOTE:

Depending on the level of fuel in the tank, it may take up to three minutes to notice a visible decrease in flow rate.

If any flow is shown on meter, a leak is present in the system. Locate the leak.
If no flow is shown on the meter, proceed to the following steps.

-- After the pressure has stabilized, set control valve -2- to "Hold".

-- After five minutes, the pressure must not drop below 8 in. (20 mbar) H₂ O.

If pressure drops below 8 in. of water in five minutes then find leak with the smoke tester, soapy water and/or isolating components by clamping them off individually.

If fuel system pressurization does not stabilize:

-- Verify all fuel system outlets have been sealed before continuing.

CAUTION:

Clamp only soft rubber lines when isolating a leak. To avoid risk of damage, never clamp hard plastic lines!

NOTE:

Any flow shown on flow meter indicates a leak.

If flow meter on tester registers flow near or above preset pressure:

-- Clamp off hose -arrow- leading from EVAP Canister Purge Regulator Valve 1 -N80- to intake manifold.

Pictured Example: AHA Engine in Audi A6

Fig 3: Clamp Off Hose Leading From EVAP Canister Purge Regulator Valve

Courtesy of AUDI OF AMERICA, LLC

If no flow is present and the pressure drop is above 8 in. of water after five minutes:

-- Replace EVAP Canister Purge Regulator Valve 1 -N80- and repeat test before continuing.

If meter indicates no flow after test:

-- Perform a quality check and return vehicle to customer.

If flow continues, proceed as follows:

-- Refer to METHOD 1: LOCATE LEAK WITH SMOKE GENERATOR .

-- Refer to METHOD 2: LOCATE LEAK WITH ULTRASONIC TESTER .