Fuel level measurement

Which zuke motor and gauges do you have? SMG4 gauge?
You are reading the fuel tank level on the zuke digital gauge? But don't have fuel burn?
The engine is 140 DF140B. The gauges are analog. Don't know how I could determine burn rate. Wish I could!
 
Thanks, everyone, for weighing in! I dipped the tank this morning and it seems to be at least half full, perhaps more, so the gauge is fairly accurate at this level. I'm going to run it down to 1/4 and measure again.