A pump assembly for a fluid tank extends along a longitudinal axis and includes a cover at an external end, the cover including a flange that extends radially outward of the longitudinal axis, an insertable end opposite the external end along the longitudinal axis, and a rotatable arm that is flexible such that, when the rotatable arm is resiliently bent such that the rotatable arm has a radial extent, from the longitudinal axis, that is less than the flange, the sender assembly is in a compact state in which the insertable end and the flange would be able to move straight along the longitudinal axis, which is coaxial with a center axis of an opening of the fluid tank, from a position where the insertable end initially enters the opening to a position where the flange engages the fluid tank.