The most reasonably priced component used on the Xrv750 Africa Twin 1990 (l) Italy Fuel Tank/fuel Pump is the Washer,plain,8mm.
On this parts fiche the Clamp D 12.0 Tube is the most specified component.
A sample from the products for the Fuel Tank/fuel Pump include: Pkg,fuel.reserve, Tube E,fuel, Washer,plain,8mm, Washer Tank Set.