is the new pump a 2 or 3 wire? If 3-wire, make sure you are wired to the switched brown wire and not the auto float brown wire.

Also, having a breaker and fuse is redundant. The bilge only needs one, of the proper value, pre-switch. However, of the breaker is for the switched manual bilge and the inline fuse is for the auto, both are needed as they are 2 different electrical circuits.