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    Just a query car wise.. Fuel guage

    Banned
    My girlfriend bought a ford fiesta today.

    Alls good.

    Pulled off the forecourt, fuel guage is fine, half a tank all good, drove to Leicester all fine, no problems.
    Got back petrol guage is fine, started creeping up on the way back.
    Got home, all good.

    Then girlfriends gone to work and the petrol light has come on, and the guage has obviously dropped down.

    Any info on this?
    Im a bit baffled, i just said well fill it up, and if it continues to go "wampy", theres a 1 month guarrantee.

    Could it just be thats its sat on the forecourt for a bit, needs a good run, and perhaps was low on fuel and air was interfereing or something?

    Regards

    19 Comments

    Most places i know only put 1 gallon of petrol in your when you buy it unless its brand new or you've struck a deal with the car place. If your car has been run really really low before you bought it then filled with petrol then pockets of air form in the tank. making you sensor think their is more petrol than there is, once the air pocket busts then you get a correct reading.
    i wouldn't worry but keep an eye on it and reset the trip mileage upon filling you tank up to compare miles per tank.

    Banned

    He meant reset, not rest Don't need a fuel gauge it's for wimps. Do 300 miles then refuel.

    It sounds to me like the fuel tank breather pipe is either blocked, kinked or obstructed. It's nothing too serious but it will affect the gauge reading. I'd speak to the garage who sold you the car, it's also a good sign that the car hasn't been serviced properly.

    Original Poster Banned

    Yeah ive told her to fill up and see how it goes, if it drops or increases like it shouldnt.. then it will be taken back.

    lumoruk;4515087

    He meant reset, not rest Don't need a fuel gauge it's for wimps. Do … He meant reset, not rest Don't need a fuel gauge it's for wimps. Do 300 miles then refuel.



    ooops cheers :oops:

    Banned

    Fuel gauges are notoriously innacurate.
    Fill up til the gun switches off.
    Reset the odometer.
    After about 300 miles fill up again, write down the ammount put in and the miles travelled and reset the odometer.
    Work out the mpg.
    Find out how much a tank holds and from the MPG work out how far you should be able to go on a full tank.
    Compare this with the MPG that you are supposed to be able to achieve. From then on merely reset the odometer when you FILL UP and then just FILL UP when you're about 50 miles from your projected max distance.
    If you calculate your MPG every time you fill up you can be warned of any fault developing if you get fewer mpg than you expect.

    PS, I've never heard of "pockets of air" affecting fuel gauges but I've only been driving since 1965. ;-)

    Pluun;4515218

    Fuel gauges are notoriously innacurate.Fill up til the gun switches … Fuel gauges are notoriously innacurate.Fill up til the gun switches off.Reset the odometer.After about 300 miles fill up again, write down the ammount put in and the miles travelled and reset the odometer.Work out the mpg.Find out how much a tank holds and from the MPG work out how far you should be able to go on a full tank.Compare this with the MPG that you are supposed to be able to achieve. From then on merely reset the odometer when you FILL UP and then just FILL UP when you're about 50 miles from your projected max distance.If you calculate your MPG every time you fill up you can be warned of any fault developing if you get fewer mpg than you expect.PS, I've never heard of "pockets of air" affecting fuel gauges but I've only been driving since 1965. ;-)



    you've obviously havn't been a student running on every last drop of fuel

    Banned

    Actually I have been a student but that doesn't change the dynamics of a box of liquid.
    Think about it, unless you're doing media studies.
    It's a box, all it holds is a liquid and a floating ball on an arm.
    Now......where exactly do the "Pockets of air" form?
    Thank you for the laff. ;-)
    I'm waiting for someone to suggest "blipping" the acceleraror when turning off next. lol

    Pluun;4515401

    Actually I have been a student but that doesn't change the dynamics of a … Actually I have been a student but that doesn't change the dynamics of a box of liquid.Think about it, unless you're doing media studies.It's a box, all it holds is a liquid and a floating ball on an arm.Now......where exactly do the "Pockets of air" form?Thank you for the laff. ;-)I'm waiting for someone to suggest "blipping" the acceleraror when turning off next. lol


    All boxes that hold liquid for the intention of supplying the liquid to another component or part always have a pipe that is quiet small, this is where the air pocket is created. Oh yeah let me guess, you studied rocket science.

    kroozing;4515807

    All boxes that hold liquid for the intention of supplying the liquid to … All boxes that hold liquid for the intention of supplying the liquid to another component or part always have a pipe that is quiet small, this is where the air pocket is created. Oh yeah let me guess, you studied rocket science.



    And that has what to do with fuel gauges exactly? It a floating ball like in a bog tank with an electrical connection to the dash :roll:

    Fuel sensor :thumbsup:

    http://images.channeladvisor.com/Sell/SSProfiles/53000259/Images/1/v221012.jpg

    esq3585;4516650

    Fuel sensor :thumbsup:



    Ford fuel sensor/pump... :thumbsup:

    http://www.allworldautomotive.com/images/userphotos/9890_12184.jpg

    Just like a bog float :giggle:

    Back to the ops original question, try jiggling the plug that connects to the pump. It should be under the back seat covered by a black rubber disk.

    Original Poster Banned

    ill give it a go when i see her later.
    Thanks for your replies guys.
    If it plays up will go back to garage for a check over.
    Cheers

    Banned

    kroozing;4515807

    All boxes that hold liquid for the intention of supplying the liquid to … All boxes that hold liquid for the intention of supplying the liquid to another component or part always have a pipe that is quiet small, this is where the air pocket is created. Oh yeah let me guess, you studied rocket science.



    No, I didn't and you certainly never will, including anything that requires a basic understanding of anything.
    Any air in the fuel delivery pipe will not affect the fuel gauge reading, which is what this post is all about.
    Do try to concentrate on the subject. ;-)

    Pluun;4516820

    No, I didn't and you certainly never will, including anything that … No, I didn't and you certainly never will, including anything that requires a basic understanding of anything.



    lol if only you knew who i really were

    anyway op hope you get it sorted without it costing you whatever it is. please post your findings

    kroozing;4517180

    lol if only you knew who i really were



    Don't even go there :lol:

    [QUOTE=Pluun;4515218]Fuel gauges are notoriously innacurate.
    Fill up til the gun switches off.
    Reset the odometer.
    After about 300 miles fill up again, write down the ammount put in and the miles travelled and reset the odometer.
    Work out the mpg.
    Find out how much a tank holds and from the MPG work out how far you should be able to go on a full tank.
    Compare this with the MPG that you are supposed to be able to achieve. From then on merely reset the odometer when you FILL UP and then just FILL UP when you're about 50 miles from your projected max distance.
    If you calculate your MPG every time you fill up you can be warned of any fault developing if you get fewer mpg than you expect.

    Just got a new car and want to work out mpg so will try - thanks.

    Goodness me, air bubbles causing inaccurate fuel gauges?
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