Fuel Pressure, Checking

Special Tools And Workshop Equipment Required 

• Diesel Pressure Tester Kit:VAS6551 
• Diesel Pressure Tester Kit - Hose 2:VAS6551/2 
• Diesel Pressure Tester Kit - Adapter Set - Adapter 1:VAS6551/5-1 
• Diesel Pressure Tester Kit - Adapter Set - Connection Hose 2:VAS6551/5-2 
• Diesel Pressure Tester Kit - Adapter Set - Connection Hose 3:VAS6551/5-3 
• Diesel Pressure Tester Kit - Adapter Set - Connection Hose 4: VAS6551/5-4 
• Vehicle Diagnostic Tester
• Measuring Container
• Wiring Diagram

Test conditions:

• The engine control module DTC memory does not contain a DTC memory entry related to the power supply of the fuel pump.
• Fuel Pump Control Module -J538- is OK
• Battery charger connected. Refer to BATTERY .
• Fuel pump fuse OK; for the fuse assignment. Refer to Wiring Diagram.
• Fuel filter OK.
• Fuel tank minimum ³ /₄ full.
• Ignition is switched off.

-- Remove the fuel supply line -1- from the fuel filter.

Fig 1: Fuel Supply Line -1-

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the :VAS6551  with the :VAS6551/2  , the :VAS6550/5-2  and the :VAS6550/5-1  as shown.

Fig 2: Pressure Testing

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Open the shut-off valves "A" and "B" on the : VAS6551  in the flow direction.

Fig 3: Identifying Diesel Pressure Tester Kit

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-- Close the shut-off valve "C".

-- Press the On/Off  button to switch on the :VAS6551  .

-- Switch the ignition on.

-- Connect the Vehicle Diagnostic Tester and conduct the guided function "activate fuel pump".

-- Select the "Check fuel pressure" function.

-- Read the pressure on the :VAS6551  . Specified value: approximately 4.0 bar

-- Slowly close the shut-off valve "B" on the : VAS6551  .

-- Read the pressure present on the : VAS6551  . Specified value. Greater than 6.0 bar.

-- Switch off the ignition.

If the specified value is obtained:

-- Check the fuel delivery rate. Refer to FUEL DELIVERY RATE, CHECKING .

If the specified value is not obtained:

-- Remove the :VAS6551  again and then reconnect the fuel supply line to the fuel filter.

-- Make sure the hose clamps are securely fastened.

-- Remove the right rear seat or rear bench seat. Refer to REAR SEATS, REMOVING AND INSTALLING .

-- Fold the right carpet cutout to the side.

Fig 4: Identifying Locking Flange Cover - Tightening Sequence

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-- Loosen the nuts -1 through 4- on the flange cover.

-- Remove the flange cover.

-- Disconnect the fuel supply line -2-. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, DISCONNECTING .

Fig 5: Fuel Lines

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-- Connect the :VAS6551  with the :VAS6551/5-3  and the :VAS6551/5-4  as shown.

Fig 6: Pressure Tester

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-- Open the shut-off valves "A" and "B" on the : VAS6551  in the flow direction.

Fig 7: Identifying Diesel Pressure Tester Kit

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Close the shut-off valve "C".

-- Switch the ignition on.

-- Perform the guided function "activate fuel pump" again.

-- Select the "Check fuel pressure" function.

-- Read the pressure on the :VAS6551  . Specified value: approximately 4.0 bar

-- Slowly close the shut-off valve "B" on the : VAS6551  .

-- Read the pressure present on the : VAS6551  . Specified value. Greater than 6.0 bar.

-- Switch off the ignition.

If the target values are achieved:

-- Check the fuel supply line from the fuel tank to the fuel filter for possible damage.

If specifications are not obtained again:

-- Make sure all couplings and fuel lines in the fuel tank and the fuel delivery unit are secure and not leaking.

If no error can be found:

-- If the fuel pump is faulty, replace the fuel delivery unit. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .