O-ring for residual fuel delivery adjusting screw, replacing

WARNING: This page is about a different car, the 1996 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The numbered items in the procedure that follows refer to Figure in DIESEL INJECTION PUMP, SERVICING .

Mark position of fuel delivery adjusting screw (e.g. position of screw slot relative to pump cover -arrows-).
Loosen lock nut, rotate against locking sleeve and unscrew fuel delivery adjusting screw from pump cover.

Fig 1: Locating Position Of Fuel Delivery Adjusting Screw

CAUTION:

The slightest misadjustment of the fuel delivery adjusting screw can cause soot build-up and/or loss of engine power.
It is important that the adjusting screw is re-installed in the same position. The fuel delivery adjusting screw should NEVER be rotated past the starting position.

Replace O-ring -24-. See Figure .
Screw in fuel delivery adjusting screw.
Run engine until warm and check idle speed and maximum engine speed.