My 1981 280 Sl 107 cuts out the petrol pumps at 65 litres whe filling from empty. I had the tank opened and found no problems inside. I blew through all the lines connected to the plastic tank which sits on top and is connected to the tank. I can slowly dribble the last 15/20 litres in if I have got all day. The car starts and runs 100% cold and hot. The cap is good and no vacuum when removed . Got me beat . All advice or wild guesses welcome Sean.