Teritorian

Hello all, I just recently bought an LN106 twin cab 97 model, which originally had the natural 2.8 litre (3L), but now has the turbo 3.0 litre (5L) The problem I have is that the tacho isnt working. is there a fix that anyone knows about? I am also only getting 400klm to a tank of highway driving....although I think the tank is tiny. Thanks in advance