Residual Pressure

• Fuel pressure OK and the VAG 1318 is still connected. Checking fuel pressure, refer to FUEL PRESSURE .
  Fig 1: Identifying Fuel Injector Pressure Gauge V.A.G 1318 And Adapter Set V.A.G 1318/17A

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- 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.

-- Watch the pressure drop on the VAG 1318.

• After 10 minutes the pressure must not drop below a 3.0 bar decrease.

If the pressure drops further 

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

-- Immediately close the shut off valve on the VAG 1318. Lever will then point in position -B-.

Fig 2: Identifying V.A.G. 1318

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

If Pressure Drops Again 

-- Check the fuel pipe to high pressure pump for leaks.

If no malfunction can be found:

-- Replace the high pressure pump. Refer to HIGH PRESSURE PUMP .

If Pressure No Longer Drops Now 

-- Check the fuel line to fuel filter for leaks.

If no malfunctions are found in the fuel line:

-- Check the check valve in the fuel delivery unit. Connect the VAG 1318 with the VAG 1318/17 between the fuel filter and 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.

-- 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.

-- After the pressure has built up, immediately close the shut off valve on the VAG 1318.

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

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Watch the pressure drop on the VAG 1318.

• After 10 minutes the pressure must not drop below a 3.0 bar decrease.

If the pressure drops:

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

If the pressure does not drop:

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