Fuel Gauge Issues...

I know there's challenges here with the tank and liquid volume, but I refuse to believe after roughly a century of application that we can't solve this problem. What about a liner inside the tank that measures weight of the liquid? I'm no engineer, that's just one idea that popped into my head, but there's no way we can design a touchscreen headunit, or queef charging, and not an accurate fuel gauge.

 

My truck always seems to be on the y u no have gas face

 

It would probably be easier to install a metered fuel pump or flow gauge or something that can keep track of fuel consumed. Much easier to know how many gallons you put in, and how many you have used, then figure out what's left, And your average MPG. Should be easy for a trip computer.

 

It doesn't bother me that much, that's how my 4runner was. But the digital gauge on the mfd will show that I have like 25 miles left when realistically I have like 3 gallons left. I know because when I fill up after being that low it will only take 18 gallons or so

 

This is from "How Stuff Works;"
The sending unit is located in the fuel tank of the car. It consists of a float, usually made of foam, connected to a thin, metal rod. The end of the rod is mounted to a variable resistor. A resistor is an electrical device that resists the flow of electricity. The more resistance there is, the less current will flow. In a fuel tank, the variable resistor consists of a strip of resistive material connected on one side to the ground. A wiper connected to the gauge slides along this strip of material, conducting the current from the gauge to the resistor. If the wiper is close to the grounded side of the strip, there is less resistive material in the path of the current, so the resistance is small. If the wiper is at the other end of the strip, there is more resistive material in the current's path, so the resistance is large.
When the float is near the top of the tank, the wiper on the variable resistor rests close to the grounded (negative) side, which means that the resistance is small and a relatively large amount of current passes through the sending unit back to the fuel gauge. As the level in the tank drops, the float sinks, the wiper moves, the resistance increases and the amount of current sent back to the gauge decreases.
This mechanism is one reason for the inaccuracy of fuel gauges. You may have noticed how your gauge tends to stay on full for quite a while after filling up. When your tank is full, the float is at its maximum raised position -- its upward movement is limited either by the rod it's connected to or by the top of the tank. This means that the float is submerged, and it won't start to sink until the fuel level drops to almost the bottom of the float. The needle on the gauge won't start to move until the float starts to sink.

Something similar can happen when the float nears the bottom of the tank. Often, the range of motion does not extend to the very bottom, so the float can reach the bottom of its travel while there is still fuel in the tank. This is why, on most cars, the needle goes below empty and eventually stops moving while there is still gas left in the tank.

Another possible cause of inaccuracy is the shape of the fuel tanks. Fuel tanks on cars today are made from plastic, molded to fit into very tight spaces on the cars. Often, the tank may be shaped to fit around pieces of the car body or frame. This means that when the float reaches the halfway point on the tank, there may be more or less than half of the fuel left in the tank, depending on its shape.

Yes, it's kinda long winded, but I hope it helps.

 

This is new? I've NEVER owned vehicle that had a linear rate of fuel gauge drop, from 1969-2016. The only difference is now it doesn't vary as much if I'm on a hill...

 

Freakin nerds

 

This is the same on every vehicle I've ever owned. The fuel gauge display is not a linear function...it is more similar to an exponential function where the closer you get to empty, the faster the needle drops. Especially on my 1968 GTO. It takes about 100 miles to get to half tank and then the needs drops to empty in about 30 miles lol

 

I honestly can't see how we can conclude that each point on the gas gauge equates to miles driven. It's a measure of volume of liquid fuel in the tank. There are lots of parameters that go into determining how much gas is used and the efficiency of a given tank will constantly change.

 

so have I but most of the older ones got far worse MPGs so the needle moved off full quicker. Also you would have to consider different tank sizes. My boat is similar in that it will drop faster in the middle of the scale versus the ends. On the boat it is more on the bottom side. I am so use to it that it does not bother me any more.

 

My 1930 Buick has a KS fluid gauge for the gas gauge. There is a small tube on the daah filled with a fluid of a specified specific gravity in the tube which has a calibrated scale beside it. A capillary tube runs to the tank. The varying air pressure in the tank based on how much gas is there causes the column of fluid in the tube to rise and fall. Cool, huh? How do I tell how much gas I have? Simple. I remove the gas cap and tap on the filler neck and listen to how hollow the sound is. We've come a long way baby. I love my Tacoma.

 

My moms 50K BMW does the same thing. In fact I have not seen a car or truck that actually gives a truly accurate fuel reading.

 

Important distinction:
Fuel Gauge is the level of fuel remaining in the tank as detected by the fuel level sending unit. Fuel gauge is NOT the percent of total fuel storage volume currently occupied by fuel.

 

Doesn't bother me I look at the fuel remaining on my Ultra Gauge. Fuel gauges with a float have always been inaccurate.

 

My 1st Gen Taco fuel gauge was almost exactly the same as the OP's graphic.

 

You really need to find a pre-1962 Volkswagen and forget to reset the reserve lever.

 

Or a Harley...

Of course, the fuel gauge on a Model T was a stick...

 

If your tank has perfect square tank and float was paper thin then it would read as you imagine it should, but because auto makers have to compromise on design and technology capability you get what you see as inaccurate. You would be surprised how inaccurate fuel gage is on boats with "v shaped bottom" gas tank when your gage is telling you you have 1/2 tank in reality you have 1/4

 

Just curious, what where your 15 previous vehicles?

 

Love the OP rant and graphic.

Personally I don't think of it as a gas gauge. I think of it as an indicator as to whether I'm going to refill yet.