A fuel tank includes a vessel having a wall, the wall includes at least a
first layer forming a hydrocarbon barrier, and a second layer that is more
permeable to hydrocarbons than the first layer and is located on an
outside of the first layer. The fuel tank also includes an insert defining
a passage between an inside of the vessel and an outside thereof. The
insert includes a first end overmolded by the wall and a second end
opposite to the first end projecting outside the vessel. The wall has a
portion extending inside the insert around an opening of the wall, the
insert being configured to form at least one region of reduced thickness
in the second layer along a diffusion path for hydrocarbons diffusing
along the second layer from an edge of the wall adjacent to the opening
towards the outside of the vessel.
