I had this issue on my Spider and all the courtesy cars I had.
This problem is well known by Alfa Romeo. It only applies for V6 and four weal drive where the tank is separated into two compartments due to the four weal drive axle. There is an automatic valve between the two tank compartments. When filling the tank the valve will fill up both of the tanks. When the valve is not working you are only able to fill ½ the tank or so. Been told that this issues is solved in the 2008 model.
Never had a problem filling up my JTDM or S-V6 Breras, but after reading this thread I thought I'd run it almost dry and fill it up.
This morning it went from light flashing to totally full without the hint of a problem (other than paying for it) No cut-outs until it reached the pump spout, when I had to struggle to get another 50p worth in it, which totally filled it.
Has the S-V6 not got the same tank as the other V6 4WD Breras?
No, not yet. Still haven't finished the last tank. (I am on holiday this week, so no commute).
Having the same problem with mine. Total garages do work best but I don't want to have to search for a Total garage all the time.
Has the revised part been a success? Could do with knowing before I take this up with the dealer.