A fluid tank system, comprising: a fluid container that includes a sensor opening in a fluid container wall defined by a rim; a fluid level sensor comprising a radial flange on a proximate end of a longitudinally extending stem that includes a distal end; a guide tube that radially surrounds the longitudinally extending stem and axially contacts a flanged surface of the longitudinally extending stem located within the fluid container, where the longitudinally extending stem, the guide tube and the sensor opening are co-axial about a central axis, wherein the fluid container comprises a first end having the sensor opening and a second end opposite the first end, wherein: the longitudinally extending stem is a longitudinally extending electronics stem; the guide tube extends from the sensor opening to the second end of the fluid container and contacts the second end of the fluid container; a proximate end portion of the guide tube located at the sensor opening has a first inner diameter and a distal end portion of the guide tube opposite the proximate end portion has a second inner diameter and wherein the first inner diameter is greater than the second inner diameter, and the guide tube comprises a plurality of fluid leak holes (386, 387, 388) configured to allow fluid to enter the guide tube. a fluid container that includes a sensor opening in a fluid container wall defined by a rim; a fluid level sensor comprising a radial flange on a proximate end of a longitudinally extending stem that includes a distal end; a guide tube that radially surrounds the longitudinally extending stem and axially contacts a flanged surface of the longitudinally extending stem located within the fluid container, where the longitudinally extending stem, the guide tube and the sensor opening are co-axial about a central axis, wherein the fluid container comprises a first end having the sensor opening and a second end opposite the first end, wherein: the longitudinally extending stem is a longitudinally extending electronics stem; the guide tube extends from the sensor opening to the second end of the fluid container and contacts the second end of the fluid container; a proximate end portion of the guide tube located at the sensor opening has a first inner diameter and a distal end portion of the guide tube opposite the proximate end portion has a second inner diameter and wherein the first inner diameter is greater than the second inner diameter, and the guide tube comprises a plurality of fluid leak holes (386, 387, 388) configured to allow fluid to enter the guide tube. the longitudinally extending stem is a longitudinally extending electronics stem; the guide tube extends from the sensor opening to the second end of the fluid container and contacts the second end of the fluid container; a proximate end portion of the guide tube located at the sensor opening has a first inner diameter and a distal end portion of the guide tube opposite the proximate end portion has a second inner diameter and wherein the first inner diameter is greater than the second inner diameter, and the guide tube comprises a plurality of fluid leak holes (386, 387, 388) configured to allow fluid to enter the guide tube.