Fuel Pump Check Valve, Checking

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-- Remove the rear bench seat. Refer to Removal and Installation .

-- Remove the cover -1- from the fuel delivery unit. The arrow -2- points in the direction of travel.

Fig 1: Removing Cover From Fuel Delivery Unit

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- First, pull on the connector -arrow- without pressing the retainer to make sure it connected securely. If the connector was not connected correctly, it could cause a fault.

Fig 2: Fuel Pump Control Module Connector

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Disconnect the connector.

-- Check the contacts on the connector and the fuel delivery unit for damage.

-- Install the test instrument adapter/DSO (5-pin) VAS 5565 between the connectors on the fuel delivery unit and cover.

Fig 3: Connecting Remote Control V.A.G 1348/3A To Test Instrument Adapter/DSO (5-Pin) VAS 5565 And To Battery Plus (+)

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the remote control V.A.G 1348/3A to the test instrument adapter/DSO (5-pin) VAS 5565 and to battery positive (+).

WARNING:

The fuel system is under pressure!

Always wear protective eyewear and protective clothing to prevent injuries and fuel from coming in contact with your skin.
Before loosening line connections, place a cloth around the connection point. Then release pressure by carefully pulling off the line.

-- Disconnect the fuel supply line -arrow- from the fuel filter.

Fig 4: Fuel Supply Line At Fuel Filter

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the pressure tester VAS 6550 to the fuel supply line using the adapter VAS 6550/1. Hold the other end of adapter VAS 6550/2 in the measuring container.

Fig 5: Connecting Pressure Tester VAS 6550 To Fuel Supply Line Using Hose VAS 6550/1

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Close the shut off lever -A- on the pressure tester VAS 6550 so the lever is perpendicular to the direction of flow.

-- Operate the remote control in short intervals, until a pressure of approximately 4 bar has built up.

WARNING:

Danger of spraying when opening the shut off lever; wear protective goggles and protective clothing to prevent injuries and contact with skin. Hold the container in front of the free connection of the pressure measuring device.

-- If pressure builds up too high, lower the excess pressure by carefully opening the shut off lever.

-- Watch the pressure decrease on the pressure tester.

After 10 minutes the pressure must not drop below a 3 bar decrease.

If the pressure drops further:

-- Check the line connections for leaks.

If no fault is detected in the wiring:

-- The fuel pump is faulty, replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT .