The VW injection pump

Introduction

The VW injection pump is an electronicallly controlled bosch VE distributor pump. The basic design was used in all 1996-2003 North American VW diesels. 2004 and later VW TDIs used the pumpe duse injection system which had no injection pump because the fuel injectors acted like injection pumps. See for more details on distributor pump, pumpe duse, and common rail systems.

Minor changes are mounting and electrical connector changes. The biggest changes are between the 11mm automatic and 10mm manual transmission pumps. The 11mm pump moves more fuel. All top cover seals and fuel temperature sensors are interchangeable and easily replaced. The quantity adjusters are also interchangeable in all models but the electrical connectors are different in the 1Z/AHU engine for 1996-1999 engines and ALH 1998-2003 engines. The cold start injector and fuel shut off solenoid are also user serviceable. All other seals and internal parts are harder to service so professional rebuilding and maintenance is recommended.

Below is a rough translation description of a rebuild of a renault 1.6L diesel injection pump. It is similar to a VW injection pump but has slightly different internals and is not electronically controlled. I can't read French, if you can, the original post is from this French site:

Here is a picture of the pump disassembled to give an idea of how many parts are inside.

First, clean everything thoroughly.

Start with one of the fuel output hard lines. Below is shown the various parts from one of the hard line: the valve, valve end, and a new joint and threaded connection.

Assembled:

Start by reassembling the stator of the transfer pump:

(pay attention to the position of the holes relative to the holes at the bottom of the pump housing, circled in green)

then the rotor and its pallets:

first place in the rotor:

then add the pallets using a grip with needle nose pliers:

then the lid of the pump:

in position with its screws

Now the main shaft:

For assembly, note the two keys and the assembly grease.

then the disc spacer

and finally the key:

Place it in the injection pump

Assembled:

Now you need to assemble the door rollers:

Places the roller in, paying attention to the position of the hole

places the assembly in the pump housing:

Note the position of the roller: it is sometimes in, sometimes out.:

The door roller, when advanced, has to be able to fit in here:

Note that the axis is pointing up:

The piston in place:

Pay attention to its position! Note the hollow part of the piston which receives the spring and it's relation to the active hole of evacuation to the transfer pump:

Again, check the axis in its place.

Lock it with the pin

And lock the pin with its clip:

Use a new o-ring here:

On the other side, the spring and other parts.

Then finally the electric "surcalor". Some models may have this part or a stopper.

Then this part which finishes this section:

Then add the rollers. They are shown here on their support separated from the pump: pay attention to the relation of the disc which is bent to adapt to the supports: