Residual Pressure in Fuel Delivery Unit, Checking:

WARNING: This page is about a different car, the 2023 Volkswagen Atlas. However, it is still accessible from the selected car via links, so may be relevant.

-- Remove the installation opening cover. Refer to FUEL DELIVERY UNIT COVER, REMOVING AND INSTALLING .

-- Remove the Fuel Pump Control Module -J538- with the connected wiring harness. Refer to Fuel Pump Control Module -J538-, REMOVING AND INSTALLING .

-- Remove the Fuel Pump Control Module -J538- toward the inside between the fuel tank and the floor panel.

-- Move the Fuel Pump Control Module -J538- together with the wiring harness to the side.

CAUTION:

The fuel system is under pressure.

Risk of injury from fuel spraying out.

- Wear protective eyewear.

- Wear safety gloves.

- Reduce the pressure: place clean cloths around the connection point and carefully open the connection point.

-- Pull the fuel line -1- off the flange. Disconnect the connector couplings. Refer to CONNECTOR COUPLINGS, DISCONNECTING .

Fig 1: Fuel Lines to the Fuel Delivery Unit

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-- Connect the :VAS6550 to the fuel delivery unit -1- using the :VAS6550/3-4 .

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Connect the :VAS6550/3-3 between the :VAS6550 and the fuel line -2-.

-- Pull on the connector couplings to check them for secure fit.

-- Make sure that the drain valve -C- on the :VAS6550 -1- is shut.

Fig 2: Identifying Shut-Off Valves A And B On Pressure Tester Kit

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-- The shut-off valves -A and B- on the :VAS6550 -1- are opened.

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

-- Close the shut-off valve -B- on the pressure gauge immediately after the pressure has been reached. The lever is perpendicular to the flow direction.

-- Repeat the residual pressure check. Refer to Test Sequence: .

If the Pressure No Longer Decreases:

-- Check the fuel line for leaks.

If the Pressure Drops Again:

Fig 3: Identifying Delivery Unit Fuel Hoses

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-- Open the fuel delivery unit -1-. Refer to FUEL DELIVERY UNIT/FUEL LEVEL SENSOR, REMOVING AND INSTALLING .

-- Make sure all hose connections -arrows- are connected.

-- Check the fuel lines for leaks and damage.

If No Error Can Be Found:

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