07 fuel lines

I have a 07, my fuel line started leaking. Went to replace and it seems the line from tank is a suppose to be 3/8, but went to replace fitting in nylon hose but the 3/8 connector was to big, when I put fitting to hose it was larger than hose, a 5/16 was also a very tight fit even after heating tube up. The problem is that I measured line up top going near fuel rail and it measured 9mm(.345 inch) and 5/16(.312 inch) has anyone run into this problem? Also looked at a diagram for fuel lines and it shows 3 lines from tank and I only seem to have 2. Any solutions? Thanx