You can alter how much it 'smokes' on the fuel pump body by altering the timing and amount of fuel provided. Apparently. I have not had much success. This is the only thing I am worried about MOT wise lol
Might be better getting a diesel specialist to look at the injectors and pump and tweaking it.
Or run a bit or paraffin or injector cleaner in the tank and take it for a good razz immediately prior to MOT. Also change your air filter
Although post up what it actually failed on please
If it's a non turbo 12J engine if i remember from one of my previous 90's the pumps are sealed units, as in you cant change the pump like you can on a 200/300. I may be wrong though!
I have a 12j and there are 4 bolts around the pump body, you can slacken these off to move it ever so slightly this was done to mine and I ended up smoking like a tar barrel turned it back to how it was and it's a lot better
Thanks thats the link ive been looking for and have told folk to look for.
I did have it saved but old lap top when tits up
I need to print it out or somthing for my mate for his 300 tdi ( he dont do computers)