Fuel tank sending unit??
 

My 1977 911 fuel tank sending unit never seems to go below 1/2 full. I followed the article on Pelican parts by Terry Steer "Repairing the Fuel Tank Sending Unit" The unit itself look new, but I took it apart and everything look ok. I tried to check it out of the tank, with the float in different positions. I could not get the fuel tank to register empty or get the low fuel light to come on. On the sending unit, there are 5 leads, only 3 are wired with the plug in my vehicle. A black, a green and a brown wire. The lead on the sending unit that is the ground, is not connected to the plug?? Granted the car is an oldie, and alot of work has been done before I got the car, but why would you have 5 leads and only 3 of them wired? Is there a simple answer?
ANYONE??? Can anyone help me fix this!