Half tank and Less
Thread Starter
Melting Slicks
Joined: Apr 2007
Posts: 2,678
Likes: 1
From: Atlanta Georgia
Half tank and Less
The other thread about instant and avg mpg got me thinking about my tank. Has anyone ever noticed how quickly the tank display drops after it reaches half tank. For example lets say i got 20 mpg and so its a 400 mile tank. My tank will read the top half of the tank as gettin 230 but than the bottom half gettin 170. anyone ever notice this?
Team Owner
Joined: Feb 2006
Posts: 23,239
Likes: 117
From: San Antonio Texas
Every car I've ever owned has been like that. You'd think with all the fancy electronics they'd have figgured out how to make an accurate gas gauge by now. At least mine is acurate on the lower half of the gauge. I tested mine by filling and checking 1/2 gallon at a time and the bottom half is dead on...one gal for one bar. Above half it "gets better mileage". It'll go almost 100 miles on the highway before it drops a bar. After that, it starts telling something a little closer to the truth.
Race Director
Joined: Oct 2005
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
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Advanced
Joined: Mar 2008
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From: Bowling Green Kentucky
Safety Car
Joined: Feb 2005
Posts: 4,721
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From: Beautiful Down Town "SWINDLEHURST" Long Island NY
A extreme example -- stick your finger in the bottom of a funnel (
don't say it ) fill with water - then let the water drain out-- the second half drains faster
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Michael S. Palmer
Safety Car
Joined: Nov 2005
Posts: 4,590
Likes: 48
From: W MI
You think they would be able to have it feed through a program that takes the level recorded and figures volume factoring in the contours. Doesn't need high level calculus, they could just find where each gallon point is through experiment and interpolate values inside of that.
Safety Car
Joined: Sep 2002
Posts: 4,971
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From: The reason time exists is so everything doesn't happen at once
With the gas sloshing around in the tank any sort of gauge that tries to measure the amount by the "level" of gas is bound to have some inaccuracy. When my gauge gets near 1/4 tank it can go from 2 bars to 4 just by going up or down a hill. Two possible soultions:
a. a collapsible bladder that would keep the gas from sloshing so the gauge can get a more accurate reading
b. a gauge that calculates the volume of gas by weight.
a. a collapsible bladder that would keep the gas from sloshing so the gauge can get a more accurate reading
b. a gauge that calculates the volume of gas by weight.
Pro
Joined: Dec 2004
Posts: 674
Likes: 1
From: Daytona Beach Florida
I saw them test the fuel pump on HorsepowerTV. they checked the reading it was sending (w/ an OHM meter) to the computer while they were moving the float throughout its range, there was a gap in the reading. It showed FULL until 1/2 a tank, then it started working from 1/2 a tank to empty...Faulty pump..they checked their new pump and the reading changed throughout the full range of motion... no gap.. oh ya and the "sock" had a hole in it and it was all rusty inside.
Instructor
Joined: Jul 2007
Posts: 118
Likes: 0
From: Plumas Lake CA
I always thought it was because the float doesn't actually go to the top of the tank (i.e. there is extra gas above the float), so it won't start sinking and reading any change until that fuel is used up. So it appears like you use gas faster at the bottom, but you're really not.