The first step is to depressurise the fuel system. Start by removing the fuel pump fuse and start the engine.
The engine will start for a few seconds until it burns all remaining fuel.

Drain the remaining fuel by using the old electric fuel pump and a suitable container.

Raise the rear of the car. The good old way of a jacking stand and a piece of wood under the wheel can do the job.

Begin by removing the tank lower hose along with the plastic fuel filler neck; it is highly advisable to renew the rubber elements.

Loosen the straps holding the tank in place and remove tank from the car. 

Note the different routing of the Marelli IAW (temporary tank).

The fuel sender has been permanently attached to the ripe routing.
When the tank has to come out there is no need to undo the bolt from the fuel sender but just from the chassis which is easier to access.

Use bubble wrap sheet to slide the tank under the car.

The underside covered by the tank has been thoroughly cleaned.

New fuel tank straps are in position awaiting for the tank.

Tank just seated in place.

Fuel pump feed line is attached and properly clamped.

Do the same to the fuel pump hose.

New ID 8 mm fuel hose. Note again that the black line is for the fuel supply and grey line for the return.

New fuel tank lower hose and clamps.

Fuel tank lower hose in place with the clamps properly tightened and blue relief hose attached to fuel filler tube all properly zip tied.

New fuel hose (ID 8 mm) is installed to the fuel pump outlet.

Finally the fuel tank straps are properly tightened.