This is for the 130 and 174 engines I can't remember if it's the same on the others.
The fuel filter lives on the passanger side just to the right of the coolant bottle and it's a reasonably easy job to change. To get at it, take the two coolant bottle screws out and move it out of the way. (No need to disconnect hoses/wires from the bottle). Take the battery cover off and slide up the little cover shown in the first pic.
It's really important to keep everything dust/dirt free once you take off the pipes so it's a good idea to give the top of the fuel filter a good blast off with brake cleaner before you start. Don't use carb cleaner since that melts some plastics.
Note the positions of the pipes (they are marked with letters) I don't think the four pipes will go back in the wrong positions but you can mark dots or whatever on them if you are the nervous type. The pipes come off by pressing in the button on the side of each one firmly and pulling them upwards. Next release the tention on the single spring clip that holds the filter and lower it enough to take the fuel filter out.
Change over the clip to the new filter and clip it into its bracket facing the right way. Some filters have an arrow on the side which points to the front. The pipes just push back on. Line them up straight as you push them home so you don't damage the seals in the pipes. Fit three of the pipes but leave the back pipe off. This way you can fill the filter up buy turning the ignition on until fuel gurgles out of the filter at the back. Pack rag aound the filter to catch any spillage. You may need to switch the ignition on and off a few times to speed things up using the pump on 'prime'. Pop the last pipe back on and away you go. You may get a few seconds of uneven running but this will soon smooth out.
Important- Make sure to clean up any spilled diesel fuel (Use the brake cleaner again) because diesel fuel can turn coolant hoses to jelly!
When you refit the coolant bottle don't forget to make sure that the small lower coolant hose hasn't popped out of its two plastic clips.
Ask away if I've missed anything out...
Edited by T5 TDI - 21 Jun 09 at 08:09