Fuel Pressure

WARNING: This page is about a different car, the 2008 Volkswagen Jetta, 2008 Volkswagen GLI, 2007 Volkswagen Jetta, and 2006 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.

WARNING:

The fuel supply line is under pressure. Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before disconnecting, place a cloth around the connection point. Then release the pressure by disconnecting the connection.

-- Disconnect the supply line -2- and catch any leaking fuel using a cloth.

Fig 1: Identifying Fuel Supply Line

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

NOTE:

Press in the securing ring to disengage the fuel line.

-- Install the VAG 1318 with the VAG 1318/17A.

Fig 2: Identifying Fuel Injector Pressure Gauge V.A.G 1318 And Adapter Set V.A.G 1318/17A

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Open the shut off valve on the VAG 1318.

-- Switch the ignition on and off until the fuel pressure on the VAG 1318 no longer rises.

-- Read off the fuel pressure on the VAG 1318.

Specified value: 3.5 to 5.0 bar

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

If the Specified Value is Exceeded

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

If no malfunction can be found:

-- Pressure relief valve in the fuel filter is malfunctioning, replace the fuel filter.

If the Specified Value is Not Obtained

-- Check the fuel pressure in front of the fuel filter. Connect the VAG 1318 with the VAG 1318/17 between the fuel filter and the fuel supply line.

Fig 3: Identifying High Pressure Fuel Gauge Connected Between Fuel Filter And Fuel Supply Line

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Open the shut off valve on the VAG 1318. The lever points in the direction of flow.

-- Start the engine and run at idle speed.

CAUTION:

The shut off valve must be closed slowly. At a fuel pressure of 8 bar, the shut off valve must be opened again immediately to prevent damage to pressure measuring device.

-- Slowly close the shut off valve on the VAG 1318. Pressure must increase to a min. 6.0 bar. If 6 bar is reached, open the shut off valve again immediately!

Fig 4: Identifying Closed Shut-Off Valve Of Pressure Measuring Device

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

If the pressure has increased:

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

If the pressure does not increase:

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