Adrien:
i just ordered one from Book4Cars.com- sent back a note to inform they are out of stock on this book - not holding my breath if they get one soon
There are some on ebay from time to time- someone has a manual on CD on Ebay - dunno if it will cover the turbo diesel or the fuel system
i know it is a Bosch electronic injector pump and in the BMW 2.4 Tdi ( not sure if it is same pump) this pump would fail due to seals- It can be rebuilt- aprox 500-700$ depending - what is the matter with your fuel system if I may ask- I have yet to get the 85 year of your Xj - just bought one of Ebay and have yet to retreive - but i am well versed in diesels
good luck
peace