2007-12-04 03:42:56 · 6 answers · asked by JE 4 in Cars & Transportation ➔ Other - Cars & Transportation
If is not that you are filling the tank 3/4 of the way, but you are putting in enough fuel to have the gas gauge read 3/4.
Fuel gauges are not very accurate. They use a float to determine fuel level and the fuel tanks themselves are usually oddly shaped!
2007-12-04 03:51:23 · answer #1 · answered by fire4511 7 · 2⤊ 0⤋
You people are all nuts, except for Fire and Steve. The reason the fuel gauge reads like this is because the fuel tank is not a perfectly shaped box or cylinder. It has odd-shaped uneven sides, top, and bottom. The fuel gauge is a simple float like the one in your toilet tank. The fuel gauge measures the level of the fuel, not the volume. Car makers are forced to make the tanks all kind of funny shapes in order to fit them into the car, and the bottom of the tank needs to have a low point so the fuel runs to the bottom and is concentrated and gets picked up by the fuel pump. All this means is that there is less fuel volume below the halfway point of the tank than there is above it. In order for a fuel level gauge to measure precisely how much fuel has been used and how much is remaining, the tank must either be a perfect cylinder or box with exactly the same volume above and below the halfway point or the gauge would have to be related to a flow meter that accurately measures fuel flow to the engine. Otherwise, a close approximation and an idiot light based on the level of fuel, not the volume, is often all you get, even on the most expensive cars. Flow meters are expensive options that are normally combined with some sort of on-board computer that calculates your fuel mileage and estimated range.
2007-12-04 06:44:49 · answer #2 · answered by Me again 6 · 2⤊ 0⤋
Yup, Fire's got it dead on. That's also the same reason why it seems like your gas gauge doesn't move much after driving when you have a full tank, but that last 1/2 or 1/4 tank seems to dissapear rather quickly.
2007-12-04 04:06:05 · answer #3 · answered by Steve 2 · 2⤊ 0⤋
Because fuel guages don't use a linear approach, but a logarythmic approach. This way it takes "forever" for the needle to drop from the "Full" mark, but once it does it goes down fast. Its a psychologial ploy used by car manufacturers to make you think you're getting good milage.
2007-12-04 04:53:11 · answer #4 · answered by mistress_coleen_01 4 · 0⤊ 3⤋
Inaccurate fuel gauge!
2007-12-04 03:50:46 · answer #5 · answered by Wounded Duck 7 · 0⤊ 3⤋
probably because your gas gauge doesn't work right.
2007-12-04 13:04:24 · answer #6 · answered by mister ss 7 · 0⤊ 2⤋