I have had used the original fuel level indicator and it got a 10 ohm resistance in series with the fuel gauge ! and i measured the current that is flowing thought the gauge differs from 100 to 250 mA , too much higher than what i am using.
and about 3 mounth ago i have to change the fuel tank bottom because of a crack and when i was repairing the tank i opened the fuel level meter and it has indicated 90 OHMS on it and it consist of some winding around a uncunductive thing.
the ballon (the end of ) moves the contactor from first winding that are conected to the ground to the longest way that is not connected anywere some thing like this pic :
http://www.8052.com/users/farshidjh/fuelgauge.GIF



Farshid J.H.