Activate The Fuel Pump With The Output Diagnostic Test Mode To Build Fuel Pressure

-- Read the fuel pressure.

Specified Value 

• Specified value: 3 to 4 bar (43 to 58 psi).

If the fuel pressure is OK, check the residual pressure. Refer to RESIDUAL PRESSURE, CHECKING .

If Specification Is Exceeded

-- Check the return line between the fuel filter and the fuel pump for kinks or blockages.

If No Faults Are Detected

-- Pressure relief valve in fuel filter malfunctioning, replace fuel filter. Refer to FUEL FILTER .

If the Specification Is Not Obtained

-- Check the fuel pressure in front of the fuel filter as follows:

Check the Fuel Pressure in Front of the Fuel Filter

Fig 1: Fuel Supply Line At Fuel Filter

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Disconnect the fuel supply line -arrow- from the fuel filter. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, SEPARATING .

-- Connect the Pressure Tester Kit - Hose 2 VAS 6550/2 to the connection -A- on the Pressure Tester Kit VAS 6550.

-- Connect the Pressure Tester Kit - Hose 1 VAS 6550/1 to the connection -B- on the Pressure Tester Kit VAS 6550.

Fig 2: Connecting Pressure Tester VAS 6550 Between Fuel Filter And Fuel Supply Line Using Hoses VAS 6550/1 And VAS 6550/2

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the Pressure Tester Kit VAS 6550 between the fuel filter and the fuel supply line using the Pressure Tester Kit - Hose 1 VAS 6550/1 and the Pressure Tester Kit - Hose 2 VAS 6550/2.

-- Pull on the connector couplings to make sure they are secure.

-- Make sure that the drain valve -C- on the Pressure Tester (Diesel) -1- is shut.

Fig 3: Identifying Shut-Off Valves A And B On Pressure Tester Kit

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- The shut-off valves -A and B- on the Pressure Tester Kit -1- are opened.

-- Activate the fuel pump with output diagnostic test mode to build fuel pressure.

-- Repeat fuel pump output diagnostic test mode to build the fuel pressure. Refer to FUEL PRESSURE, CHECKING .

If Specified Value Is Achieved

-- Check the fuel line between the fuel filter and the engine compartment for possible kinks or blockages.

-- Check the fuel line between the fuel filter and the engine compartment for leaks and damage.

If No Faults Can Be Found

-- The fuel filter is clogged. Replace the fuel filter FUEL FILTER .

-- Pressure relief valve in fuel filter malfunctioning, replace fuel filter. Refer to FUEL FILTER .

If the Specification Is Not Obtained

Proceed as follows to check the fuel pressure at the fuel delivery unit:

Check the Fuel Pressure on the Fuel Delivery Unit

-- Remove the bench seat. .

-- If equipped, remove the Fuel Pump Control Module -J538- -2- from the cover -1-.

Fig 4: Identifying Cover With Fuel Pump Control Module J538

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-- Unclip the right cover -1- at the tabs -arrows- using the Trim Removal Wedge 3409.

Fig 5: Identifying Right Cover

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-- Remove the fuel lines -1- from the flange. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, SEPARATING .

Fig 6: Fuel Lines At Flange

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-- Connect the Pressure Tester Kit VAS 6550 -1- between the fuel line and the fuel delivery unit using the Pressure Tester Kit - Hose 1 VAS 6550/1 and Pressure Tester Kit - Hose 2 VAS 6550/2.

Fig 7: Identifying Fuel Line And Fuel Delivery Unit

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

• Pressure Tester Kit - Hose 1 VAS 6550/1 -2- between the fuel line -5- and shut-off valve -B-
• Pressure Tester Kit - Hose 2 VAS 6550/2 -1- between the fuel delivery unit -4- and shut-off valve -A-

-- Pull on the connector couplings to make sure they are secure.

-- Make sure that the drain valve -C- on the Pressure Tester (Diesel) -1- is shut.

Fig 8: Identifying Shut-Off Valves A And B On Pressure Tester Kit

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- The shut-off valves -A and B- on the Pressure Tester Kit -1- are opened.

-- Activate the fuel pump with the output diagnostic test mode to build fuel pressure. Refer to FUEL PRESSURE, CHECKING .

If Specified Value Is Achieved

-- Check the fuel lines for possible restrictions (kinks) or blockages.

-- Check the fuel line for leaks and damage.

If Specification Is Not Obtained

-- Remove the fuel delivery unit. Refer to FUEL DELIVERY UNIT  and inspect it for debris.

-- Make sure all hoses -arrows- are connected.

Fig 9: Identifying Delivery Unit Fuel Hoses

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Check the fuel lines for possible restrictions (kinks) or blockages.

-- Check the fuel lines for leaks and damage.

If No Malfunction Can Be Found

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

Tightening Specifications 

• Refer to OVERVIEW - FUEL DELIVERY UNIT/FUEL LEVEL SENSOR