Joe, It sounds to me like you have a bad check valve on the old fuel pump. The early style had a fatter banjo fitting, so when you switch to the new shorter neck valve the banjo is almost too fat and only gives you about 1.5 threads for the dome nut. Now in your case since you went from a later style to an earlier style, you may already have a narrow banjo. This is only a guess, but maybe the narrow banjo is too thin and the dome nut is bottoming out before it completely tightens the connection. It is possible to have an invisible leak since the fuel can spray out in such a fine stream that it is only a vapor. And I suppose you already know that you aren't supposed to reuse the copper crush washers. Walt Tampa, FL