Calibrate fuel gage

luzt

luzt

Member
Hi!

Facts: 34L tank on a 1.2TDI

When the yellow light lits up it says I only have 120-130km left before I run out of fuel. My average is ~0,34L /10km which would indicate that I have about 4L (12*0,34=4,08) left in the tank.
But even when it says 60km left have I been able to fill in more then ~29,8L. I there by come to conclusion that my fuel gage is a tad of.


How do I go about re-calibrating it?
 
luzt said:
Hi!

Facts: 34L tank on a 1.2TDI

When the yellow light lits up it says I only have 120-130km left before I run out of fuel. My average is ~0,34L /10km which would indicate that I have about 4L (12*0,34=4,08) left in the tank.
But even when it says 60km left have I been able to fill in more then ~29,8L. I there by come to conclusion that my fuel gage is a tad of.


How do I go about re-calibrating it?
Click to expand...

Firstly, do you vent the tank when you filled it? There is a vapour expansion tank which (deliberately) prevents some of the 34 litres being used in order to allow petrol vapours to be contained on hot days without pushing the liquid fuel out of the filler tube.

Of course, on a diesel there is no use for this, and you can safety pull the little lever which vents the tank (on the inside of the fuel filler, about a 3cm in on the right). This will allow you to use more of the full capacity of your tank. Never do this on a petrol tank.


On my 1.4L w/34L tank ...

* When the pump first 'clicks off', it is usually at about the 29 litres mark
* I then dribble the fuel in, waiting for the foam to die down, and open the vapour release valve with the end of the pump nozzle
* Eventually I can get around 33-34 litres in, with time
 
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The reserve volume on the 20l tank is quite excessive too. On the fuel bong going I was able to go over 100km more and on filling only got 16l in after venting.
This indicates that the bong goes at around 4.5-5l.
As I understand running out to the point of stalling in a diesel is far more involved than simply topping up fuel on a petrol car and so an early warning is probably intentional.

John
 
I had to confirm - not re-calibrate, my fuel gauge when I upgraded humpy with the 42 litre tank and DIS.
I recall that the tank required 7 litres of fuel with the car on level ground. I then adjusted the fuel gauge settings via VCDS to get as close to accurate as I could.
There is also data on ELSA on the resistance readings of the fuel sender linked to the fuel quantity in the tank. It's a long winded excercise but will highlight if there is an issue with sender accuracy. Obviously - safety, especially with pertol fuelled cars is paramount!!

blue skies
tony
 
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