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The early wear-out of a fuel sender resistor assembly, especially the card and contact components, has been a durability and cost concern, resulting in frequent engineering redesign. This liquid level sensing device called a fuel sender, has been an expensive and annoying vehicle repair item. Not only do fuel sender designs need to be accurate and durable, designs must be capable of being produced economically. Designs with no moving fuel sender parts are not practical due to cost disadvantages. This paper describes design improvements which address the problems of premature resistor card wear-out in standard fuel sender designs. This paper does not address fuel measurement.

Design and manufacture of fuel senders include adjustments to establish accuracy of measurement of the amount of fuel in the tank and that show on the gage in the passenger compartment. The essential techniques are: 1) Electronic calibration; design and manufacturing of the resistor and matching parts to assure the response resistance matches both mechanical and electronic gage characteristics. 2) Mechanical calibration; design and manufacturing of the float arm and related geometric and trigonometric points, distances and angles that assure the position of the float at all fuel levels respective to fuel gage indication. Vehicle manufacturing firms have used angular sweep liquid level sensors for measuring fuels for several decades. These designs incorporate the capability of linearizing (via angle relationships) height and volumetric fuel tank characteristics very accurately.