Forget accuracy. My second car was nearly empty when I test drove it and liked it. It ended up with lots of problems which were hard to find. No details as it's history. But a recon engine later it was still not totally sorted. That took a fuel flush and an inline fuel filter. Bottom line is all costs from empty petrol tank.
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I've taught myself to think that 1/4 of a tank is nearly empty, as I like to have a reserve for emergencies. So I start looking for a petrol station as soon as the needle hits that mark.
It does mean I get very nervous when driving with under a 1/4 tank of fuel though.
Edited by Ravenger on 01/12/2007 at 09:49
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I don't want a stupid display that tells me I have 138 miles left, then I take my foot off the gas and it says 141, then I boot it again and it says 129. If I was so concerned about fuel consumption that I had to employ some of the (admittedly interesting) systems mentioned above for calculating what's in the tank I think I'd catch the bus. If there was one.
I know I've said this on here before but every Honda fuel gauge I've ever had has read the same way - an apparent 400 miles in the tank, about 100 miles left when the light comes on, with tank capacity varying according to engine size. All the gauges have moved in the same way, too, so I can guarantee when I pull in to fill up that I can look at the gauge, look at the tripmeter and tell to the litre how much it will take. I've never had a diesel, though, which may be different.
My Rover P6 3500 had a reserve tap, which was an excellent feature because most of the time I couldn't bear to look at the fuel gauge anyway.
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quote".......I don't want a stupid display that tells me I have 138 miles left, then I take my foot off the gas and it says 141, then I boot it again and it says 129.......unquote"
>>>>>>>>
>.........spot on
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Yes, and mh is spot on about reserve taps on thirsty cars too. My Bentley had one. The thing to avoid was leaving it open all the time.
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In reply to the OP, the Yaris manual says it starts to flash when roughly 1 gallon left and then it flashes faster as the fuel runs out.
(If in doubt, RTFM:-)
madf
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Dear madf
I have read the manual and for your benefit here is the exact wording:
"If the fuel warning light blinks, fill the tank as soon as possible. Further fuel reduction makes the light blink quicker.
If the fuel tank is completely empty, the malfunction lamp comes on. Fill the fuel tank immediatly"
The manual says nothing at all about how much fuel is remaining when the lamp starts to blink (at least it does not in my 18 month old copy).
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It's bloke entertainment for annoying your passengers. The Legacy counts down by the mile and then with 30 miles to go it just reads --. My record is getting down to 1.5 litres left in the tank by the time I filled up.
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The Almera sits on "full" for ages, then plummets to half, where it sits for a while, then it falls to the red, and the light flashes. Having driven around with the light on for days in the past, the most petrol I've filled with is 43 litres (50 litre tank). So despite a constant light, and the needle resting on the stop, I still had 7 litres left, which is about 1.5 Gallons. Or, at 40mpg, enough fuel for 60 miles!!
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>>>I don't want a stupid display that tells me I have 138 miles left, then I take my foot off the gas and it says 141, then I boot it again and it says 129.
Strange. I rather like it. If it didn't change according to your recent driving style it would be reporting the wrong figure. On my 318 it's really useful - plus you have a traditional guage too.
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just recently NASA had to cancel a shuttle mission because of a dodgy fuel gauge, why they couldnt just brim the shuttle and go is beyond me, its not as if they can do a splash and dash on the way home !!!
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I think knowing how much fuel they had, was a slight help when they nursed apollo 13 back
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< Ulla>
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i think they were more worried about how much juice they had in the batteries
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"Huston we have a problem there been an explosion"
"How much fuel do you have"
"Dunno Milkyjoe told us to top it up and go - he said it would be Ok"
"Well ok then, no problem see you back on earth"
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< Ulla>
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actually its " ok houston we've had a problem here" if you want to get all smart alec about it
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What really irritates about inaccurate fuel guages is the real fact that they effectivly make the fuel tank smaller than it is. What happens is that you see the gauge getting 'low' and so you top up, this means that the last 5, 10, or 15 litres never gets used. In effect you are driving round with unused (and unusable) ballast in the tank.
An accurate guage would be a small, but real aid to fuel economy. Such a guage would be one way of being a little bit 'greener'
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put a tenners worth of petrol in then reset your trip meter every time , you will soon calculate what your car is doing on average , i still get 100 miles to the tenner and thats allowing for fuel price increases
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put a tenners worth of petrol in then reset your trip meter .....
How do you know when you've used the tenner's worth?
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>> put a tenners worth of petrol in then reset your trip meter ..... How do you know when you've used the tenner's worth? when the needle on the gauge is back where it was before you put the tenner in .....der
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when the needle on the gauge is back where it was before you put the tenner in .....der
Very accurate, I must say!
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this means that the last 5 10 or 15 litres never gets used. In effect you are driving round with unused (and unusable) ballast in the tank.
Never gets used does it? What does it do then, sit on top of the new petrol when you fill up your tank and then gets stale or something. Come now, you're having a laugh are you not?
Don't you think, that possibly, it might mix with the fresh petrol and get consumed that way?
I don't think that I will make any more comments for fear of offending, as HJ et.al might not like it.
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Dear Old Git
I thought that my meaning was quite clear, evidently to you it is not.
I mean that the residual fuel capacity of 5, 10, or 15 litres does not get used because of the inaccuracy of the fuel guage, i.e. you are always going to be carrying an ungettable-at quantity of fuel.
Imagine that the tank is rectangular and the outlet is halfway up one side, the fuel below the outlet will just become ballast that is needlesly carried around and cannot be used. That is the analogy of having an inaccurate fuel guage.
It should be quite obvious that any particular fuel molecule will eventually make it to the engine and be consumed.
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Dear Old Git I thought that my meaning was quite clear evidently to you it is not.
Not really but then I am old old, unintelligent chemist with an addled mind. However, if your gauge is so inaccurate, then why not, when you think that your tank is empty, brim it with petrol and see just how much it takes to fill it then, you will know how far you car reasonbly go, when your gauge shows 'empty'.
(You obviously know the total capacity of your tank and the amount that is required to fill it, hence you can adjust accordingly).
QED.
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>> QED.
QED? -Semi pedant mode on/
I don't think so. Relying solely upon memory, but QED means 'Quantom et Demonstratum' (or something like that) i.e. 'to show it is to prove it' As spotty schoolboys we amended that to 'quite easily done' which I think is the interpetation you are using in your post.
ipso facto ;-)
Edited by drbe on 20/12/2007 at 09:54
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drbe, I would like to make the proposition that your memory isn't very good. As evidence I offer your statement "Relying solely upon memory, but QED means 'Quantom et Demonstratum' ......."
Q.E.D is in fact short for "Quod erat demonstrandum"
Q.E.D! ;-)
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QED - Quod Erat Demonstrandum (Latin: Which Was to Be Demonstrated )
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QED - Quod Erat Demonstrandum (Latin: Which Was to Be Demonstrated )
How's about QEF, then - look that up!
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Since randomly changing the fuel pump and sender on my Mondog in an attempt to make it start (it didn't, new sparks did) I now have a fuel gauge that mostly works backwards!
I fill her up and the red light comes on, then, as I drive around town, she gradually creeps higher and higher until I have an almost full tank, then I know it's time to fill up again.
Interestingly the computer is working the other way round, starts with a high range which gradually reduces to nothing.
Blue
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Quod Erat Faciendum (Latin: Which Was to Be Done)
45 years on my old Latin Teacher , Mr Dodds would be proud of me.....
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I offer several simple solutions:
1) The gauge has a removable glass but no markings. You run the tank empty, then put in 1 gallon (or x litres) at a time, and make a mark at each point. They won't be evenly spaced, but it will compensate for any shape of tank.
2) Use a similarly calibrated stick, as most boat owners do
3) Have a clear section of tank - just get out and look at the level
4) Tap the tank and listen to the point where the note changes from dull thud to a higher pitch (that's what I do with my garden rainwater tank)
5) External transparent stand-pipe, like on central heating oil tanks.
6) Piezzo-electric effect (is that the right principle here?). The fuel tank is mounted on say 4 special pressure sensitive devices which thereby weigh the tank and contents and convert the weight to volume equivalent.
7) Bell-shape connecting an air pipe to a pressure sensitive variable resistor outside the tank. Like the device used in washing machines, only better made, of metal not rubber of course.
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You all expect that your electricity meter, your gas meter, your water meter and your telephone meter (at the exchange) to be accurate. You all expect the garage fuel pump to be accurate when buying fuel, so why are so many of you prepared for such inaccurate rubbish in a vehicle costing ££££££££?
I am not interested in methods of calculating how big my tank is, or in estimating how much fuel is left so as to be able to compensate for a rubbish guage, all I want is an accurate guage in the first place.
We have Sat-Nav systems accurate to a metre or so, yet we cannot get a fuel guage to show anything more meaningful than 1/1, or ½, etc. We see wonderful new cars by the day, we hear Top Gear rabbiting on about this and that super new wizzo thing, yet we seem to accept without any complaint a 'guage' which is a disgrace to accuate measurement.
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Why not do it by weight? After all, thats what aeroplanes do (big ones) - and little ones come to that, but also with a dipstick.
Surely you could measure the empty weight of a fuel tank - and then just have a gauge that converts weight to gallons, and then have a readout on the dash. Can't remember how much a gallon or fuel weighs - but worth a thought eh?
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That was my suggestion No. 6
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6) Piezzo-electric effect (is that the right principle here?). The fuel tank is mounted on say 4 special pressure sensitive devices which thereby weigh the tank and contents and convert the weight to volume equivalent.
I was thinking on similar grounds but with strain gauges.
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Mike Farrow
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how about an electronic rev counter on the fuel pump? surely that would produce accurate metering
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Doesn't the fuel circulate on modern injection systems, particularly diesels? If so, that wouldn't work. How about accurate flow meters on the fule lines?
Edited by nick on 22/12/2007 at 16:16
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