Pressure Retention Test

Fig 1: Identifying Evaporative Emission (EVAP) Canister Purge Regulator Components

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Set valve -D- to "Test". Increase the current pressure until it reaches 10 in. H2O (25 mbar).

-- 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.

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

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

If the pressure is not maintained for 5 minutes, the leak should be localized as follows:

-- First, check the EVAP canister purge regulator valve 1 for leaks. Using a hose clamp up to 25 mm dia. 3094 -arrow-, clamp off the hose to the EVAP canister purge regulator valve 1.

Fig 2: Clamping Off Hose To EVAP Canister Purge Regulator Valve 1 -N80- Using Hose Clamps Up To 25 Mm Dia. 3094

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Repeat the pressure test by resetting 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- :

• If the flow quantity decreases and pressure increases to 10 in. H2O, then the fuel system is full.

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

If the pressure no longer drops now: 

-- Replace the EVAP canister purge regulator valve 1.

If the pressure still drops: 

-- Perform the "fuel system leak test". Refer to FUEL SYSTEM LEAK TEST .

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