Volvo Repair: fuel line replacement/repairs, flare wrench, volvo 245

Question
1978 Volvo 245

I'm attempting to replace both the external and internal
fuel pumps as well as the fuel lines running between the
tank and the primary pump under the car.

So far I've been unsuccessful in removing the access cap at
the top of the tank as it's rusted (the part that twists out--
it has three lines running from it-- my question concerns
one of these lines)

One line runs from the tank to the primary pump, the other
runs to (from?) the accumulator... however, the third seems
to connect with the front of the car and I can't seem to
remove it (it seems to be a solid line). How do I go about
replacing this line and what exactly does it do?

Answer
The third line is a plastic hard line that needs to be removed from under the car above the rear axle. Has a metal fitting on end of it. Use 14mm and 15mm wrenches, use flare wrench to not strip it.
If everything is rusted, maybe you should get a new sending unit at the same time.