got my mk2 festa yesterday

but on way home noticed the petrol gauge doesnt work...ooops! it did come on quickly then went off again so the guage must work so must be something else. maybe a signal or power wire loose connection? is there a sender unit in the petrol tank somewhere? giv me help plz!! and im after an xr2 lump and woteva else u need to turn it in to the 1.6 xr...gearbox etc. does anyone know anywhere i can get stuff like that around the birmingham area?? thnx ppl