A fluid tank system comprises a fluid container that includes a sensor opening in a fluid container wall defined by a rim, and a fluid level sensor comprising a radial flange on a proximate end of a longitudinally extending electronics stem that includes a distal end. The distal end of the electronic stem is inserted into the fluid container via the sensor opening and the radial flange seats on the rim. The distal end of the electronics stem is guided via a first radial support and a second radial support to a seat that is located coaxial with the sensor opening, where the first and second radial supports are longitudinally separated and radially spaced apart to allow the electronics stem to longitudinally pass between the first and second radial supports until the flange seats on the rim ensuring that the distal end of the electronic stem is longitudinally positioned adjacent to the seat.