Fuel Gauges

[Jahee]

They are quite unreliable depending on whether you are on a gradient / camber... Isn't there a more accurate way of measuring!?

 

[Mackie2k]

Yes, stop and suck out the fuel. That will give you an accurate reading.

 

[Stunt]

Most people don't care for a precise measurement.
They just want to know when to fill up.
Full, 3/4, half usually means nothing to the average driver.

 

[Jahee]

Originally posted by: Stunt
Most people don't care for a precise measurement.
They just want to know when to fill up.
Full, 3/4, half usually means nothing to the average driver.

I suppose... it can't be hard to measure by different means though... weight for example!

From Full to 3/4 goes reeeally slow, but then 3/4 to half goes in about 60 miles! its really annoying lol..

 

[Fayd]

sound above the fuel, to determine the empty space in the tank and calculate based on that.

course, there's baffles in the tank to prevent sloshing.. so that'd make that kind of hard.

 

[Stunt]

Originally posted by: Jahee

Originally posted by: Stunt
Most people don't care for a precise measurement.
They just want to know when to fill up.
Full, 3/4, half usually means nothing to the average driver.

I suppose... it can't be hard to measure by different means though... weight for example!

From Full to 3/4 goes reeeally slow, but then 3/4 to half goes in about 60 miles! its really annoying lol..

Talk about changes on inclines...
Elevation would screw over your weight readings. Not in your city, but in the rockies for example.

 

[Jahee]

Originally posted by: Fayd
sound above the fuel, to determine the empty space in the tank and calculate based on that.

course, there's baffles in the tank to prevent sloshing.. so that'd make that kind of hard.

What do you mean by baffles?

 

[EagleKeeper]

One can determine the amount of fuel used but how do you determine what is placed into the tank without an additional meter. Is it worth the cost?

 

[OrganizedChaos]

suspend the tank by a spring scale.

 

[TraumaRN]

Or get a car that just tells you how many miles you have left on a given tank of gas that changes dynamically based on your driving.

My girlfriend Ford Fusion has this and it's awesome.

 

[Jahee]

I'd imagine just hav standard weights for a fuel stored, the ECU can determine which grade of fuel is used as it already does, might not be so much more additional cost?

 

[Syringer]

Originally posted by: Jahee

Originally posted by: Stunt
Most people don't care for a precise measurement.
They just want to know when to fill up.
Full, 3/4, half usually means nothing to the average driver.

I suppose... it can't be hard to measure by different means though... weight for example!

From Full to 3/4 goes reeeally slow, but then 3/4 to half goes in about 60 miles! its really annoying lol..

Gas tanks are usually built in the shape of a V..and since the sensor is just vertical, the meter will go down slower in the beginning.

 

[giantpinkbunnyhead]

Originally posted by: Jahee

Originally posted by: Fayd
sound above the fuel, to determine the empty space in the tank and calculate based on that.

course, there's baffles in the tank to prevent sloshing.. so that'd make that kind of hard.

What do you mean by baffles?

Baffles are like partitions, designed to separate the tank into smaller sections so as to minimize fuel sloshing from one end to the other. With baffles, the fuel will only slosh over a couple inches.

On larger aircraft, fuel cells contain multiple fuel quantity sensors, and they "average" out readings from different locations in the tank. When we depart in a 727 and climb out at a 20 or 25 degree angle, our gauges don't budge at all, save for normal fuel burns. But it would probably not be cost effective to implement that into vehicles, especially since the consequences of running out of fuel in a car pale in comparison to running out of fuel in a plane. When it comes to vehicles, the "best" indicator, I think, is the number of miles driven since you last filled up.

 

[Jahee]

Originally posted by: DeathBUA
Or get a car that just tells you how many miles you have left on a given tank of gas that changes dynamically based on your driving.

My girlfriend Ford Fusion has this and it's awesome.

Some newer cars over here have that standard, however i find that to be more unreliable than fuel gauges... it changes too frequently, it changes with every adjustment of the pedal, really hard to judge.

 

[Jahee]

Originally posted by: giantpinkbunnyhead

Originally posted by: Jahee

Originally posted by: Fayd
sound above the fuel, to determine the empty space in the tank and calculate based on that.

course, there's baffles in the tank to prevent sloshing.. so that'd make that kind of hard.

What do you mean by baffles?

Baffles are like partitions, designed to separate the tank into smaller sections so as to minimize fuel sloshing from one end to the other. With baffles, the fuel will only slosh over a couple inches.

On larger aircraft, fuel cells contain multiple fuel quantity sensors, and they "average" out readings from different locations in the tank. When we depart in a 727 and climb out at a 20 or 25 degree angle, our gauges don't budge at all, save for normal fuel burns. But it would probably not be cost effective to implement that into vehicles, especially since the consequences of running out of fuel in a car pale in comparison to running out of fuel in a plane. When it comes to vehicles, the "best" indicator, I think, is the number of miles driven since you last filled up.

How do they measure the quantity out of interest? pressure?

 

[Jahee]

Originally posted by: Syringer

Originally posted by: Jahee

Originally posted by: Stunt
Most people don't care for a precise measurement.
They just want to know when to fill up.
Full, 3/4, half usually means nothing to the average driver.

I suppose... it can't be hard to measure by different means though... weight for example!

From Full to 3/4 goes reeeally slow, but then 3/4 to half goes in about 60 miles! its really annoying lol..

Gas tanks are usually built in the shape of a V..and since the sensor is just vertical, the meter will go down slower in the beginning.

Built in the shape of a V?? is this something you've seen personally, not a very efficient use of space... would make sense they are rectangular, starting on the bottom of the back seats running down to the floor?

 

[Tom]

"Baffles are like partitions,"


no, they're like brazzieres, they keep stuff from sloshing about.

 

[giantpinkbunnyhead]

Originally posted by: Jahee

Originally posted by: giantpinkbunnyhead

Originally posted by: Jahee

Originally posted by: Fayd
sound above the fuel, to determine the empty space in the tank and calculate based on that.

course, there's baffles in the tank to prevent sloshing.. so that'd make that kind of hard.

What do you mean by baffles?

Baffles are like partitions, designed to separate the tank into smaller sections so as to minimize fuel sloshing from one end to the other. With baffles, the fuel will only slosh over a couple inches.

On larger aircraft, fuel cells contain multiple fuel quantity sensors, and they "average" out readings from different locations in the tank. When we depart in a 727 and climb out at a 20 or 25 degree angle, our gauges don't budge at all, save for normal fuel burns. But it would probably not be cost effective to implement that into vehicles, especially since the consequences of running out of fuel in a car pale in comparison to running out of fuel in a plane. When it comes to vehicles, the "best" indicator, I think, is the number of miles driven since you last filled up.

How do they measure the quantity out of interest? pressure?

Heh, good question. I had to bust out the flight manual for that one, and even that didn't answer the question so I called our maintenance foreman. He told me that our 727's don't use floats or pressure; they use electric probes and capacitance to generate a reading. The probes measure the quantity of milli-amps, which depends on how far immersed into the fuel the probe is. Then a computer elsewhere takes the milliamp reading from all the probes and turns it into a "pounds of fuel" readout on the gauge. I'll have to study that more as I only partially understand what's at work here.

 

[ultimatebob]

Originally posted by: DeathBUA
Or get a car that just tells you how many miles you have left on a given tank of gas that changes dynamically based on your driving.

My girlfriend Ford Fusion has this and it's awesome.

My Audi A4 has one of those, and it's painfully inaccurate. My car often says that I have 440 miles of fuel range after I fill it, but I only average 325 miles before the low fuel light comes on. Even with flat highway driving, I can't crack 380 miles before that low fuel light comes on. When that low fuel light comes on, the trip computer usually says that I have 40 miles left. I've driven it over 50 miles after that light comes on, and I still had a gallon left in the tank when I finally filled it! In other words, the computer is way too optimistic about the range when you first fill it, and gets overly pessimistic once the tank gets low.

Amusingly, my old Mercury Cougar had a trip computer as well, and that one was far more accurate at guessing my range. Go figure.

 

[duragezic]

I don't really like depending on my miles since fillup since my MPG can vary drastically. Most of the time is town driving in snow/cold with many hills, so MPG drops big time. Other times is letting the car idle to warm up, or leaving it running when I run into a store for a few minutes (this is probably unheard of for you city folk 🙂). And occasionally when I travel home, it is constant highway, so MPG is way up. My light comes on when ~2.3 gallons remain, but that can go on and off for the first while as I stop/go and with inclines. Given ~22/31 MPG I have plenty of time to get to a station before completely running out (needle past E). I've probably been within 10-20 miles of completely empty once when my light came on and I went another 50 miles because this indian reservation gas station I wanted to make it to has uber cheap gas, cigs, and alcohol. But I ended up stopping somewhere about 6 miles before that place because I didn't wanna run out.

A somewhat accurate way to measure would be like the airplane does. This place I did a co-op at was developing an oil level sensor. There was a long gold/silver plated plane on the circuit board with some traces inside the board. I forgot the details of it but I did a bunch of work on it. It used capacitance (dieelectric of oil or fuel is obviously different than air) to determine how much of that plated plane was submerged. I did some testing on it and it ended up being extremely accurate (to like .01" or more?) and had a R^2 ratio of like .9997. Turns out somehow there realized the whole thing is f*cked when you are on an incline or stop/go, thus it would be easy to have the indicator LEDs give false info for inclines and whatnot. So that project got canned or shelved! :\ The equations done by a engineer there were only like 7 pages worth... he explained them to me and they were quite easy to understand and derive. Cool stuff anyhow.

 

[RaiderJ]

Originally posted by: Jahee

Originally posted by: Stunt
Most people don't care for a precise measurement.
They just want to know when to fill up.
Full, 3/4, half usually means nothing to the average driver.

I suppose... it can't be hard to measure by different means though... weight for example!

From Full to 3/4 goes reeeally slow, but then 3/4 to half goes in about 60 miles! its really annoying lol..

You must have a Chevy! I think every one I've been in does that.

 

[Black88GTA]

Originally posted by: ultimatebob

Originally posted by: DeathBUA
Or get a car that just tells you how many miles you have left on a given tank of gas that changes dynamically based on your driving.

My girlfriend Ford Fusion has this and it's awesome.

My Audi A4 has one of those, and it's painfully inaccurate. My car often says that I have 440 miles of fuel range after I fill it, but I only average 325 miles before the low fuel light comes on. Even with flat highway driving, I can't crack 380 miles before that low fuel light comes on. When that low fuel light comes on, the trip computer usually says that I have 40 miles left. I've driven it over 50 miles after that light comes on, and I still had a gallon left in the tank when I finally filled it! In other words, the computer is way too optimistic about the range when you first fill it, and gets overly pessimistic once the tank gets low.

Amusingly, my old Mercury Cougar had a trip computer as well, and that one was far more accurate at guessing my range. Go figure.

My BMW 840 has one of those too. It's a pile of crap. Right when I got the car, I was on a long distance drive and was running low on gas in no-man's land, Pennsylvania. It was late at night, and there were very few exits, and even fewer open gas stations. I knew there was a 24 hour truck plaza coming up in ~20 miles or so, and my trip computer said I had 45 miles remaining till empty. Great, I thought, no problem...

...until my car sputtered and ground to a halt - with the stupid trip computer saying I had enough gas left in the tank to go 34 more miles. :roll: Never trusted that crap again.

 

[XZeroII]

Get a long stick and jam it down into the gas tank. That is the most reliable way to find out how much gas you have left.


OR!!! Put a video camera in there so you can see exactly how much is left!

 

[AgaBoogaBoo]

Just use the trip odometer 😉