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Hi guys,ive always had reservations on how much fuel im using,on average its about 200 miles on half a tank,whether thats good or not im not sure.Its been on a quarter of a tank today with something like 120 miles left to go,i got back in it tonight and its now on half a tank saying 310 miles left,im guessing at sender unit maybe at fault,never experienced this before.Its just had a service and runs fine apart from the overall speed,its not a flying machine,any help or ideas would be appreciated.

Working on the fuel gauge & trip computer alone can be highly misleading, the gauge is heavily influenced by how level the ground is when you turn on the ignition and the 'miles left' varies a lot according to how it was driven over the most recent journey (or the last bit of it).

I suggest filling it to the brim, reset the trip computer & reset the trip mileometer, run till it's nearly empty & completely fill again. This will let you manually calculate the mpg over a full tank & see how accurate the trip computer is too. I think they're usually pretty good - my two sets of numbers never disagree by more than about 0.5 mpg.

So much of this depends on your driving style etc etc. On my 110 LX i get on average 400 miles out of half a tank, (always use that as a guide as to how im driving!) then round about 800 - 820 before the light comes on. The fuel trip computer on mine under - reads by about 5mpg, compared to me working it out manually. I never tend to use the miles left to empty function TBH

hi thanks for your replies,im confused as to your answers,i agree that with every car you drive and how much fuel you use depends on how it is driven,my query was how can i go from having a quarter of a tank to half a tank and as of today its still on a half a tank,i personally believe its the sender unit.

parcelman wrote:Hi guys,ive always had reservations on how much fuel im using,on average its about 200 miles on half a tank,whether thats good or not im not sure.Its been on a quarter of a tank today with something like 120 miles left to go,i got back in it tonight and its now on half a tank saying 310 miles left,im guessing at sender unit maybe at fault,never experienced this before.Its just had a service and runs fine apart from the overall speed,its not a flying machine,any help or ideas would be appreciated.

My wife read this earlier, she said hers has always done this (we've had the car over four years now). She has never told me this before. She says she accepted it as a quirk.

She uses £30 of diesel and does 270 miles each week going to work and back, (all motorway).

They all tell lies, mine can be 1/4 of a tank less a few minutes after setting off.

thanks for all your replies its appreciated,its a really helpfull forum,no doubt i will be on here a lot more,m.o.t on saturady,rip of time i guess.

Hi Parcelman

I have experienced exactly the same problem when the gauge jumps from ¼ full to just over ½ full.
This is believe is an electrical problem.
There is a current thread on this in the electrics system.

Zyzym