Computer Fuel Gauge

[Glawster Taff]

I'm getting approx 47mpg on my 2.2 diesel, and with an 11 gallon tank (near as dammit) I'd expect to get well over 500 miles per tank. Trouble is the gauge shows near zero when I reach 420, and the warning light comes on soon after.
When I next fill up I can put about 44 litres in, so there seems to be around a gallon left in at each fill up. I'm thinking that maybe there's a problem with the fuel gauge, but has anyone else come across this? Nothing similar comes up if I search the threads, apart from I can get 75 miles + before the needle comes off the top of the gauge. With my triumph acclaim (Honda engine) I could get to a hundred miles before the needle moved!)

[Pottsy]

The gauge relies on a float. Incredibly, this float only moves 3" between full and empty, and just 0.1" between fuel light and empty. Remember that the tanks are fairly flat (under the front seats).

With this tiny movement, it's going to be inaccurate. Add to this the great long tube that goes from the filler to the tank (that holds fuel that cannot be measured) and the requirement to make sure the system under-reads slightly (so you don't run out) - and you are left with a reading which is only ever going to be approximate.

[ASH]

I think there is a description on owner's manual that about 5 litre fuel left when the warning comes on. That's approximately correct, isn't it?

[TTDegs]

Yep, even after running mine to empty, light on, desperately driving round the M25 (and late for meeting), I've only every squeezed a max of 47 / 48 ltrs in.

I normally fill up at about 0 miles alledgely left and get 45 ish to fit in

[pjr]

Originally Posted by TTDegs

Yep, even after running mine to empty, light on, desperately driving round the M25 (and late for meeting), I've only every squeezed a max of 47 / 48 ltrs in.

I normally fill up at about 0 miles alledgely left and get 45 ish to fit in

I can beat that - last week I put 50.55 litres in, after the trip computer had said 0 miles remaining for about 6/7 urban traffic crawl. I think the pipe from the tank to the filler cap must hold a fair bit!

Don't normally run it down that low, but got caught out on this occasion.

[Charles_Harding]

Originally Posted by Pottsy

- and you are left with a reading which is only ever going to be approximate.

Then when you run out of fuel on the motorway, you tell the Honda Assistance guy.

Sorry my approximation was too approximate!

......nipping out to fill up now!

"I don't have ulcers,
I give them!"

[mike20]

Yes this is annoying, but all cars have their peculiarities, you just have to get used to them.

One useful trick I use is to wait until the light comes on, then do about 30 miles more and then fill up with 45.5 litres which is approx 10 gallons (45.46 to be more precise).
If you reset one of your trip meters when you fill up, it means that you know how much you are doing to the gallon.

I know (before anyone points it out) that you could just use the on board computer, but I just do this as a check.

For the record I get approx 420 miles to the 10 gals and in fact this does more or less tie up with the computer reading.

2.2 i-CDTi Sport.

[Honda100]

I was always advised to be carefull about running the fuel so low as the filter picks up all the crudd (technical term I am sure!) from the bottom of the tank and gradually blocks it. High quality fuel might negate this of course.

[Clive242]

Originally Posted by mike20

One useful trick I use is to wait until the light comes on, then do about 30 miles more and then fill up with 45.5 litres which is approx 10 gallons (45.46 to be more precise).
If you reset one of your trip meters when you fill up, it means that you know how much you are doing to the gallon.

I do exactly the same, and consistently get 44-45 litres in.

However, after 2 days of sensible driving (not easy when it's so much funny Vtec-ing), I've managed to get 400 miles out of a tankful. Trip Computer said I'd got 8 miles left.
Amazed when I managed to get 49.77 litres in.

[Unknownsoldier]

I hate driving sensibly, that's why once this tanks done i'll be driving Dakar style once again.

Tom