Check what some mechanic wrote:
"hi there, i have worked on alfa/fiat for 12 years.
if the car is a petrol twin spark then they dont have a fuel filter thats changable, they have a metal gaze in the pump which is submerged in the tank so not changeable,
if its a petrol jts then they have the one in the tank, which is not changable and also one built into the high pressure pump on the side of the head, again its a gauze one and not changable.
if its a diesel then its a screw on type mounted on the back of the bulk head behind the power steering pump