I posted quite a while back of my non functioning fuel sender gauge problem. finally got the system working. Some where in its 9200 plus hour past history some one changed out the instrument panel .(Plus much other stuff) The gauges were of the wrong type for the old SW tank senders. Different operating ohm ranges as they were Rochester gauges VS the SW senders. I found a set of gauges from salvage company in B.C. from a same year/model wrecked AC. Now they read quite accurately . Now my left tank seems to fill the right tank . CFI says its just me being uncoordinated. After each flight I would hanger the C172 with out filling till the next flight. I would fill both tanks, they each took nearly equal gallons. (with in a couple tenths) Now with working gauges I see the left will empty and the right will be nearly full. It was quite a surprise to find only 5 gallons in the left tank and the right tank nearly full. So it's off to coordinated flight training .