Fuel light on/guage empty but still 11litres in the tank?!

[CraigyMc]

kambites said:

55palfers said:

I can't see the problem

Would you rather the light came on with 1 litre left?

Personally, I'd rather my fuel gauge told me how much fuel was actually left. There's no reason the light should stay off until the gauge is reading empty; in my car the light comes up with about a quarter of a tank left but the gauge is reading something like a quarter of a tank.

A quarter of a tank on your car is about 9 or 10 litres, isn't it? Similar to OPs.

In my car, the light comes on with about 10 litres left (of 61) and that's usually good enough for over 100 miles of driving (car routinely averages over 60mpg).

It'd be nice if the gauges were accurate to the litre and said something like "17 litres remaining", which is how the Lotus is supposed to work. Unfortunately, the engineering of that part of the car was a bit "mystic meg".

C

[kambites]

CraigyMc said:

A quarter of a tank on your car is about 9 or 10 litres, isn't it? Similar to OPs.

The light is similar, yes. But the fuel gauge reads correctly (at least on average, at any given time the gauge in an Elise could be reading almost anything). I've managed to get 34 litres into my 32 litre tank without being concerned about running out.

[Roger Irrelevant]

Lee540 said:

I've never seen my fuel light in 3 years.. just keep it topped up.

Then you're spending too long at the petrol station! Seriously though, because I don't do a lot of miles if I could be confident that I could get another 80-odd miles from a tank then that would often mean I could go another week before filling up - and I hate filling up!

[kambites]

Lee540 said:

I've never seen my fuel light in 3 years.. just keep it topped up.

I've never put petrol in my car without the light being on.

[Kenny6868]

I wish I had an analogue fuel guage!
My Clio has a digital one that goes down in orange blocks. When I get to 70 miles remaining the light comes on and the range displays as a row of dashes! Its guess time after that. I usually do one more commute and then fill up.

In my old Mk3 Golf I would regularly take it to under the empty line before filling up. I never once ran out.

[littleredrooster]

WinstonWolf said:

Any crap that gets in the tank will sit at the bottom, 11 litres isn't that much spread over a large tank and you don't really want it getting into the fuel lines/filter.

It's done by design to help stop the numpties from blocking their fuel systems up.

So you think fuel is drawn from the top of a tank? Really?

[kambites]

littleredrooster said:

So you think fuel is drawn from the top of a tank? Really?

I suppose there could in theory be rubbish floating on top of the petrol, but every modern fuel tank I've opened has been immaculately clean inside.

[Lowtimer]

By definition there can never be a fully accurate "miles left" because it cannot possibly know how you are going to drive from this point on, only how you have driven up to now. If you are stuck in a solid traffic jam all night and you keep your engine running then "miles left" until you run out of petrol = 0 regardless of how much you started with, or how economically you were driving up to that point.

To take a less extreme example if you are cruising down the motorway for a few hours at 60 mph and are about to turn into heavy urban stop-start traffic for the last 20 miles of a journey into London, your fuel gauge or computer doesn't know that.

What would be more useful is an accurate "gallons left" or "litres left" readout.

[conkerman]

Meh.

probably due to the fact that lift pumps have been cost optimised out of many cars and running out is a total ballache to get fuel up to the engine.

[WinstonWolf]

littleredrooster said:

WinstonWolf said:

Any crap that gets in the tank will sit at the bottom, 11 litres isn't that much spread over a large tank and you don't really want it getting into the fuel lines/filter.

It's done by design to help stop the numpties from blocking their fuel systems up.

So you think fuel is drawn from the top of a tank? Really?

http://www.subaruforester.org/vbulletin/f88/06-forester-xt-replacing-fuel-pump-fuel-filter-110334/

[Dan-P]

My Forester also does the same, the fuel light doesn't come on until the gauge is pointing at or slightly below the empty line.
The fuel light is supposed to start flashing when there is only a gallon or so left (can't remember the exact figure) but I've never got it this low even after 30-40 miles with the fuel light on steady.

[Riff Raff]

WinstonWolf said:

littleredrooster said:

WinstonWolf said:

Any crap that gets in the tank will sit at the bottom, 11 litres isn't that much spread over a large tank and you don't really want it getting into the fuel lines/filter.

It's done by design to help stop the numpties from blocking their fuel systems up.

So you think fuel is drawn from the top of a tank? Really?

http://www.subaruforester.org/vbulletin/f88/06-forester-xt-replacing-fuel-pump-fuel-filter-110334/

I think that link just shows that littleredrooster is right. The fuel pick up is at the bottom of the tank. The fact that the pick up pipe / pump / filter assembly exits at the top is neither here nor there.

[CraigyMc]

WinstonWolf said:

littleredrooster said:

WinstonWolf said:

Any crap that gets in the tank will sit at the bottom, 11 litres isn't that much spread over a large tank and you don't really want it getting into the fuel lines/filter.

It's done by design to help stop the numpties from blocking their fuel systems up.

So you think fuel is drawn from the top of a tank? Really?

http://www.subaruforester.org/vbulletin/f88/06-forester-xt-replacing-fuel-pump-fuel-filter-110334/

You just linked to a thread about a fuel pump assembly which is accessed from the top of the fuel tank (because accessing it from any other direction would cause fuel to flow out of the access hole).

In the thread it clearly shows that the fuel pickup is at the bottom of the tank.

[WinstonWolf]

Riff Raff said:

WinstonWolf said:

littleredrooster said:

WinstonWolf said:

Any crap that gets in the tank will sit at the bottom, 11 litres isn't that much spread over a large tank and you don't really want it getting into the fuel lines/filter.

It's done by design to help stop the numpties from blocking their fuel systems up.

So you think fuel is drawn from the top of a tank? Really?

http://www.subaruforester.org/vbulletin/f88/06-forester-xt-replacing-fuel-pump-fuel-filter-110334/

I think that link just shows that littleredrooster is right. The fuel pick up is at the bottom of the tank. The fact that the pick up pipe / pump / filter assembly exits at the top is neither here nor there.

It's not at the bottom, it's towards the bottom. I've drained quite a few tanks, some have been very clean, others have had detritus sitting at the bottom. Drawing the fuel in this way helps to avoid any muck that may be present.

[M6L11]

Mazdas are designed the same way. With the gauge showing empty and the trip computer saying 0 miles remaining, there are 12 litres (from a 62 litre tank) in reserve. So basically a quarter of the tank is hidden and you're living off the top three quarters at most. The manual confirms this and also says try to fill up with more than a quarter of a tank left; presumably the 'hidden' quarter rather than a quarter off the gauge, which would put it at half a tank!

The TC reading for overall MPG is, conversely, rather accurate based on brim-to-brim calculations. Regardless, I'd definitely rather have a pessimistic gauge than an optimistic one!

[kambites]

WinstonWolf said:

It's not at the bottom, it's towards the bottom. I've drained quite a few tanks, some have been very clean, others have had detritus sitting at the bottom. Drawing the fuel in this way helps to avoid any muck that may be present.

Am I being dense? Why would how much fuel is in the tank have any bearing on whether the intake picks up any rubbish on the bottom of the tank?

[WinstonWolf]

kambites said:

WinstonWolf said:

It's not at the bottom, it's towards the bottom. I've drained quite a few tanks, some have been very clean, others have had detritus sitting at the bottom. Drawing the fuel in this way helps to avoid any muck that may be present.

Am I being dense? Why would how much fuel is in the tank have any bearing on whether the intake picks up any rubbish on the bottom of the tank?

The intake isn't at the very bottom, a small quantity of possibly contaminated fuel remains. The debris is usually heavier than the fuel so it doesn't get picked up.

I'd rather have a fuel gauge that leaves me with a little in reserve.

[Riff Raff]

kambites said:

WinstonWolf said:

It's not at the bottom, it's towards the bottom. I've drained quite a few tanks, some have been very clean, others have had detritus sitting at the bottom. Drawing the fuel in this way helps to avoid any muck that may be present.

Am I being dense? Why would how much fuel is in the tank have any bearing on whether the intake picks up any rubbish on the bottom of the tank?

It doesn't have any bearing at all.

Me, I do a lot of sailing. So I spend a fair few hours a year cleaning 'stuff' out from the bottom of fuel tanks. As you can imagine in a marine environment, it's a lot easier to get contaminants (mainly water) into your fuel tank. The pick up pipe on a boat just as with cars, is always as near the bottom of the tank as makes no difference. There needs to be enough of a space to allow the fuel to float on top of whatever contaminants are in there, and to avoid these contaminants being sucked up into the fuel system in quantity. Any minor contamination that does get picked up is dealt with by the fuel filter. Filters on a boat.

The level of fuel in the tank doesn't have any bearing on how much 'stuff' the fuel filters need to separate out IME.

[S0 What]

Riff Raff said:

WinstonWolf said:

littleredrooster said:

WinstonWolf said:

Any crap that gets in the tank will sit at the bottom, 11 litres isn't that much spread over a large tank and you don't really want it getting into the fuel lines/filter.

It's done by design to help stop the numpties from blocking their fuel systems up.

So you think fuel is drawn from the top of a tank? Really?

http://www.subaruforester.org/vbulletin/f88/06-forester-xt-replacing-fuel-pump-fuel-filter-110334/

I think that link just shows that littleredrooster is right. The fuel pick up is at the bottom of the tank. The fact that the pick up pipe / pump / filter assembly exits at the top is neither here nor there.

Of course the pick up is at the bottom, it would be pretty dam useless at the top (not aimed at you but at the pratts who think letting the tank run low allows crap to be sucked up).
Fuel senders wear out or rather the tracks do and as they wear the resistance alters, some last decades some years, usually the fuel light is a seperate track so there can be differences in the 2 but usually the light comes on with 2 gallons left on jap motors IME but look in the handbook to check.
Over the last year i've changed probably 20 fuel pumps and or removed them to remove a missfuel, out of all of them the only cr@p i've found in a tank was diesel mould (turns the fuel black and blocks filters), plastic tanks simply dont get as crappy inside as steel ones used to, that's why they are made of plastic nowdays, i've yet to find a tank that's full of particulates from tesco petrol stations (insert the supermarket you hate in leu of tesco).
The main reason modern pumps pack up is running out of fuel overheats them, wears the rotor tips/siezes them.
Lastly, never come accross a car that will put the engine light up for a non working fuel gauge, the managment light sould only illuminate for an issue that affects emmisions, not that i've worked on every car,, yet.

[S0 What]

WinstonWolf said:

The intake isn't at the very bottom, a small quantity of possibly contaminated fuel remains. The debris is usually heavier than the fuel so it doesn't get picked up.

I'd rather have a fuel gauge that leaves me with a little in reserve.

bks, ni on all fuel injection systems take fuel from a sump (or low point in the tank)or from a swirlpot usually designed into the actuall pump housing so as to avoid the pump runing dry under cornering, that swirl pot sits at the very bottom of the tank, infact most fuel pumps are in a spring loaded housing to make sure they sit at the very bottom of the tank.