I'm having difficulty calibrating my restance fuel tank level. Wired tank sender to pin 20 (orange brown wire) for left tank (capacity 24 gal), filled in 2 gal increments, got ocassional messages that the sender value did not change, punched full as directed. I'm now installing a dedicated ground wire but would like to make manual empty and manual full entrys when I raise the float to the top of the tank. How are manual entrys accomplished? Many thanks Murray Randall