[BigLew]

Tiny makes a great point. Hopefully, you have not remove the old hose yet.

What you need to do is create a guide wire! Get the stiffest wire or other item you can find that will pass down through the old hose to the end. Then, take the new piece of hose, put it over the guide wire and push it into place while it pushes the old those out. The guide wire will need to be at least twice as long as the original fuel hose so that you can keep tension on the guide wire while pushing the old hose out.

When everything's in place, i.e. the fuel fill pipe is attached to the hose, then you can remove the guide wire. A suggestion for the guide wire might be 2-4 AWG wire(battery)cable or something else equally heavy and stiff.

Just my 2¢ worth. Good luck.