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Old 06-30-2008, 11:59 PM   #2 (permalink)
Master EcoModder
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Join Date: Jun 2008
Location: Northwest Lower Michigan
Posts: 1,006

Red Car - '89 Chevrolet Celebrity CL 4 door
Team Chevy
90 day: 36.47 mpg (US)

Winter Wagon - '89 Pontiac 6000 LE Wagon
90 day: 28.26 mpg (US)
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I dont think it would be worth it. There are just too many variables that give a less than perfect reading.

For starters, the shape of most gas tanks is not a rectangular box, but an odd shape designed to make the best use of space in the floorpan. That right there would make the reading be inaccurate at different points on the sender, even if the sender was perfect.

Then there is the level of vehicle, and whether you are accelerating or decelerating usually makes a difference in the reading even with the same amount of fuel in the tank. Also there is the internal baffle around the sender, and Ive noticed that the fuel will read higher if Ive stopped and restarted during a long drive, than if I just drove it straight. Stops and restarts will refill the baffle and give higher readings for awhile, then when the fuel really runs low the gauge drops much faster.

Then there is the geometry of the float arm itself. Assuming all else was perfect, the only way to get a true reading would be at the point when the float arm is horizontal. As it goes higher or lower, some of the float swing is horizontal motion, so the float (and gauge) moves more for the same drop in fuel level. The point where the gauge moves the slowest would be the point that the float arm is attached to the sender. It might be different for all cars.

Some newer cars might have better float systems anyway. I am mainly familiar with my old GMs.

Winter daily driver, parked most days right now

Summer daily driver
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