Fuel guage will not go to full when tank is full of gas. It drops very quickly and at 1/4 tank and 246 miles took only 8.5 gallons of gas. DIC gas per miles estimate is very close to miles vs gallons. The dealer changed the fuel sending unit but the guage is still not working correctly. The only problem the new sending unit helped was the msg that Check the Gas Cap is no longer coming on.

Any ideas of what is wrong. Car has only 1500 miles on it.

thanks!