For many years, fluid level measurement in fuel tanks has been accomplished using a float and lever arm to operate a variable resistor. The resistance reading is translated by any of several gauge designs. The float and lever arm sensor requires a significant amount of tank space and has accuracy and reliability problems.A new family of linear sensors utilizing various thick film materials is discussed. The devices utilize conductive plastic or cermet resistors on various substrates and may be operated as a 2-wire variable resistor or 3-wire potentiometer. Significantly less space is required and the shape of the signal output curve can be adjusted to fit a variety of tank designs. The linear sensors are adaptable to the modular reservoir fuel delivery systems now in use.