Test Procedure

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK

WARNING: Fuel system is under pressure! Before opening the system, place rags around the connection area. Then release the pressure by carefully loosening the connection. Always wear eye protection!

Start diagnosis

-- Disconnect fuel supply line -3- at the supply location and catch any fuel coming out with a shop towel

Fig 1: Identifying Breather Line, Vacuum Line & Fuel Supply Line

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

NOTE: Pull circlip upward to unlock fuel line

-- Install a fuel pressure gauge with appropriate adapters.

-- Open shut off valve on fuel gauge.

-- Switch ignition on and off repeatedly until fuel pressure stops increasing pressure.

-- Read fuel pressure on the gauge.

Specified value: 3.5 to 6 bar

If specification is exceeded:

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

If no malfunction in fuel return line is found:

-- Pressure relief valve in fuel filter is malfunctioning.

-- Replace the fuel filter. Refer to the Repair Information.

If reading was below the specification:

-- Check fuel pressure at the fuel filter between fuel pump and fuel filter using appropriate adapters

-- Open shut off valve on gauge and start the engine. Allow to idle.

-- Slowly close the pressure gauge shut off and note the fuel pressure.

Pressure must increase to 6 bar.

When 6 bar is reached: Open shut off tap immediately!

If pressure has increased during test:

-- Fuel pump is OK. Pressure relief valve in fuel filter is malfunctioning.

-- Replace the fuel filter. Refer to the Repair Information.

If pressure did not increase:

-- Fuel pump is faulty

-- Replace the fuel pump. Refer to the Repair Information.