After i refitted the fueltank to the car i canīt get the fuelgauge to work again, is there something i can do or is it over for the original sender unit?

did you connect the ground lead?
david

ohh yes, iīve connected the ground lead on two separate places but with no result, the guage shows over full tank with the sender cable connected or disconnected.

Try grounding the the cable on the sender. If the gage is working, it should go to empty.
http://www.chevelles.com/techref/ftecref18.html

Thanks! :)