Injection Pump Valves

The injection pump check valves shut off the fuel supply to the injectors at the end of injection to prevent pressure build up and fuel "dribble" at the injector nozzles, which can cause pre-ignition and high exhaust emissions. The location of the valves is shown in Fig. 5-20. The valves do not generally fail. However, their seals can become loose over time, and should be replaced or the valve body tightened if leakage is seen around them. Leaks around the injection pump valves can also cause a pressure drop in one or more injectors leading to hard starting and rough running.

Fig. 5-20.

Timing check plug (white arrow) to be removed for installation of dial indicator. Only the small central plug and its gasket should be removed. The black arrows indicate the fuel injection pump check valves.

To correct leaks:

1.	Thoroughly clean the fuel pipes, the unions, and the pump head.

2.	Loosen the nuts holding the injection pipes to the pump valve housings, then torque the housings to the pump to 45 Nm (33 ft. lb.).

3.	Re-tighten the injection pipe nuts and torque them to 25 Nm (18 ft. lb.).

4.	Run the engine and check for leaks. If there is still leakage, replace the sealing washers in the pump valves.

5.	Loosen the fuel pipe unions at the injectors and at the injection pump. Remove the fuel pipes as a unit, using care not to bend or kink them.

6.	Loosen and remove the leaking pump valve. If more than one housing is removed, be careful not to interchange parts. Fig. 5-24 is an exploded view of one valve.

7.	Install a new sealing washer and reinstall the valve housing. The washer is Volkswagen Part No. 068 130 787 A. Torque to 45 Nm (33 ft. lb.).

8.	Reinstall the fuel pipes. Torque to 25 Nm (18 ft. lb.).

9.	If leakage continues, replace the entire valve assembly. (Volkswagen Part No. 068 130 795).

Fig. 5-24.

Exploded view of injection pump valve.