I'll give it a try.

Ah, there's neither an additional pump or filter inside the tank. In fact, the flow from one part to the other takes place as a result of reverse pressure generated by the fuel filter (I don't know how) which is located outside of the tank, as the filter is.

@Cullub, I've already tried what you suggested. That screw is just for holding the plastic cover over the two wire connections.

@Myself, I've added the photos