27 replies to this topic

[carts60]

So that means that from the red, mathematically we still have 1/3 of the capacity left to burn before running on empty.

Totally useless guage

Red lining should mean empty not 1/3 full. Halfway should be halfway between full and empty and full should be full. How can you go over the top of full?? Thats not even possible but the guage still shows it.

Epic fail...

[The_Mistro]

well its different for each car, there all just a rough guide! just what i found with mine!

some cars have 5.5 gallon tanks, so find out which your car has before thinking you have a 1/3 of a tank left! lol

[danie garry]

when mine reads empty theres still 15 litres left which when i have a 33 litre tank is just a little under half gone so it really does vary on each guage

[robtheplod]

When mines on the bloodline there is actually still half a tank left! I manage to get in about £17 worth of fuel when 'empty' !!

Edited by robtheplod, 26 June 2010 - 07:27 AM.

[adam_93rio]

The red line on Most cars is the reserve fuel, not empty. I have around 1/3rd of a tank left when it hits the redline, wiring out when hit hits the redline, fill it up, you wont get more than 5 gallon in there and it's a 7 and half gallon tank
Mine often hits the redline before I fill up, i work it out that if I drive steady I'd still have about 100 miles after hitting the redline

[AndyMiniMad.]

Remember that the float in the tank will ...errrr.... float. So if the tank was a uniform shape then when the guage says half you could believe it. But it isnt...... so you cant!!!!!!!!!!!!

[Sam14]

Having gunk on the bottom of your fuel tank is only if the car has been stood for ages with leaded petrol, and i mean AGES

No way could the jets spray that into the pistons, that would be very impossible

Plus 21st century fuels have a natural cleaning chemical and no lead

If your so damn worried about it, take the fuel tank out and swill it out instead of panicking everytime it gets low?

Edited by Sam14, 26 June 2010 - 08:02 AM.

[foxfan]

Dont worry about "gunk" in your tank mate because fuel is always drawn from the bottom of your tank. It cant be drawn from the top of the tank. Trust me this is my area of expertise. Secondly, classic mini fuel gauges are not known for their accuracy. If you really want to know how accurate your gauge is, then when it gets pretty low, head out into the country lanes where you aren't going to cause a traffic headache and drive until you run out of fuel and keeping an eye on where the gauge is when the tank is dry, but making sure you have enough petrol in cans in the boot to get to a filling station.

[MiniMonty]

I fill up my car and the gauge says full.
I drive about ten miles every day and for the first couple of days it still says full.
Then suddenly the gauge just says empty - or, more accurately, "I'm very old and don't work very well".

So I forget about it (because I'm more worried about whether it's overheating in the traffic or not)
and then I give it a tenner and a blast of lead replacement juice - guess what - it says "full" again.

As mentioned before - it will cost you exactly the same to keep it topped up as to go 'full to empty, full to empty'
so just whack a tenner in every couple of days (depending how far you drive) and don't worry about it.

Having said all that I do keep a 5 litre can in the boot just in case
(and some points, and some spark plugs, and a torch, and... and... and...)

Best wishes
Monty

[danie garry]

why is every1 sayin to run it to empty??
is it not easier(and less embarassing) if u get it to the red line and then see what it takes to refil it, take that from 33(33l=7.5 gal tank) and that gives u what u have left

[Dan]

There's a fair chunk of nonsense in this thread (particularly regarding sediment in leaded fuel, wow!), will everyone please remember the notice at the top of all technical pages asking you all to only post facts?

There are already plenty of threads about this subject. All cars of all different makes have differently accurate fuel gauges. Hardly any actually give a properly calibrated fuel level, get used to your car. It really is that simple.

[miniobsessed]

To answer the original question...

We are dealing with 'primative' analogue electroincs here. The reason the marks on the gauge are not linear is because the tank is not a linear shape but the float resistance is. There is no fancy ECU or microcontroller to convert this reading into a nice linear movement to drive a stepper motor fuel gauge like on a more modern car.

Basically if you don't understand this then just read your gauge (providing it works and is something like accurate )... When it's in the red - refuel. Simple.

[1995 MK2 IOM]

I have had my clocks out... the needle comes off the dials anyway! (I presume to change the backgrounds) and can be put back in any position! surely when someone takes the needle off... they will NEVER put it back in the exact position it started at...

so basically... if the needle is out... and you know its out... you could change in that way...

mine lets me drive quite a lot after it touches the red line... but I know that I take about £34 to fill it up (from running out) any less than that is what is in my tank already...

J