When its installed it defaults to a full tank and zero fuel used. So you dont need to do anything else. If your fuel tank is not currently full, go fill it up.
As Mach440 said, put an overlay item on your screen - I just put Fuel Used there.
You can also put fuel economy there if you are interested in travelling at the most economical speed - or you can scare yourself seeing live figures for mpg
. You might be surprised to see the difference between 4800rpm and 5800rpm.
As I mentioned in my earlier post from now on,
whenever you fill up or add fuel, you must go into settings/fuel and select refuel, then either check the “set to full” button, which resets fuel used to zero and fuel remaining back to the full capacity, or “add fuel” if you put some in but dont fill all the way. It then adjusts fuel used and fuel remaining to take account of how much you told it you added.