Fuel Pressure Regulator And Residual Pressure, Checking

Fuel Pressure Regulator and Residual Pressure, Checking

Special tools, testers and auxiliary items required

• Fuel injection pressure gauge (VAG 1318)

• Valve adapter (VAG 1318/9)

• Adapter set (VAG 1318/17)

• Fuel line feed adapter (VAG 1318/23)

• Remote control (VAG 1348/3A)

• The fuel pressure regulator regulates the fuel pressure to approximately 4 bar.

• Fuel pressure regulator is located on the fuel filter. From October 2005, the fuel pressure regulator is integrated in the fuel filter and cannot be replaced.

• Observe the safety precautions. Refer to --> [ Safety Precautions ] .

• Observe the rules for cleanliness. Refer to --> [ Clean Working Conditions ] .

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

- Disconnect the fuel supply line - 1 - and catch any leaking fuel using a cloth.





• Press in the securing ring to disengage the fuel line.

- Connect the (VAG 1318) with the (VAG 1318/9) and the (VAG 1318/17) to the fuel filter - 1 - and to the supply line - 2 -.





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

- Bleed the fuel system. Refer to --> [ Fuel System, Bleeding ] .

- Start the engine and run at idle speed.

- Measure the fuel pressure.

Specified value: approximately 4.0 bar positive pressure

If the Specification is Not Obtained:

- Switch off the ignition.

- Check the delivery quantity of the fuel pump. Refer to --> [ Delivery Quantity, Checking ] .

- If the fuel pump is OK, replace the fuel filter/pressure regulator.

• From October 2005, the fuel pressure regulator is integrated in the fuel filter and cannot be replaced.

If the Specified Value is Achieved:

- Switch off the ignition.

- Now check for leaks and residual pressure (entire system). Observe the pressure drop on the (VAG 1318).

After 10 minutes there must be a residual pressure of at least 3.0 bar.

If the holding pressure drops below 3 bar:

- Start the engine and run at idle speed.

- Wait until pressure has built up, then switch off the ignition. Simultaneously close the shut off valve on the (VAG 1318) (lever perpendicular to direction of flow) - arrow -.





- Observe the pressure drop (engine side) on the (VAG 1318).

If the pressure drops again:

- Check the line connections, O-rings on the fuel rail and fuel injectors for leaks. Refer to --> [ Fuel Injectors, Checking Injection Quantity and for Leaks ] .

- Check the (VAG 1318) for leaks.

• Before removing the (VAG 1318), place clean clothes around the connection which is to be disconnected.

If the pressure does not drop:

- Check the line connections to the fuel tank and check valve of the fuel pump. Refer to --> [ Fuel Pump Check Valve, Checking ] .

- If the check valve is OK, replace the fuel filter/pressure regulator.

• From October 2005, the fuel pressure regulator is integrated in the fuel filter and cannot be replaced.

- Bleed the fuel system. Refer to --> [ Fuel System, Bleeding ] .