EM TuningAH Fabrications
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  1. #1
    Izzy1's Avatar
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    Fuel tank question....

    hi guys,
    i'm hoping this is a simple question.
    was filling up my car last night and i always fill to the brim. i noticed a little button thing on the left of the opening. what is it? and what does it do?

    cause when i hit it by accident it seemed to suck my fuel through... allowing me to put more fuel in the tank.

    if anyone can shed some light on this i'd be greatful.
    Izzy

    Bora TDI sport
    Audi A4 TDI

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  3. #2
    Broken Byzan's Avatar
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    Thats the centeral locking pin. When the car is locked so is the cap

  4. #3
    Izzy1's Avatar
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    when i pressed it, it was taking in air. made an air intake noise. if you know what i mean.
    Izzy

    Bora TDI sport
    Audi A4 TDI

  5. #4
    denzelburner's Avatar
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    Quote Originally Posted by Izzy1 View Post
    hi guys,
    i'm hoping this is a simple question.
    was filling up my car last night and i always fill to the brim. i noticed a little button thing on the left of the opening. what is it? and what does it do?

    cause when i hit it by accident it seemed to suck my fuel through... allowing me to put more fuel in the tank.

    if anyone can shed some light on this i'd be greatful.
    The little button is the thing that vents your fuel tank of air when you put the fuel filler cap back on. As you screw it in, it presses it down and vents.
    It seems to suck your fuel in, as it is replacing the space the air was taking up at the top of the fuel tank. This only happens if you are filling it right up, otherwise there is sufficient space in the tank for both the fuel and air, until the fuel tank pressure has built up enough for the fuel to work it's way up the filler neck. the fuel in the neck then replaces the air when the vent returns the tank to a more atmospheric pressure, hence how you can put 'extra' fuel in.

    Hope i'm not teaching you how to suck eggs, and it explains this useful
    phenomenon
    If you can't beat them, arrange to have them beaten

    2000 B5 2.5tdi V6 (if only it were a quattro)

  6. #5
    Izzy1's Avatar
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    and as simple as that he knew what that "button" was for. lol

    thanks.
    Izzy

    Bora TDI sport
    Audi A4 TDI

  7. #6
    denzelburner's Avatar
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    No worries
    If you can't beat them, arrange to have them beaten

    2000 B5 2.5tdi V6 (if only it were a quattro)

  8. #7
    jcb
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    oo oo, a new toy to play with on my car.
    learn something new everyday

 

 

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