On my old Grady with two tanks, I could tell you almost exactly how much fuel was left in each tank when it indicated it was empty.
Like you, my 283 only has one tank and I'm too chicken to run it out completely.
I have decided to ignore the bars and use the "fuel used/remaining" function of the Garmin 4210. I think it gets its information from the same sensor that the Yamaha gauge uses, but for some reason, it seems to be more accurate. The Yamaha gauge usually shows a little less fuel used than the Garmin does.
When I fill up, the Garmin is usually within .5 to .75 gallons of what it takes to fill it up. I have set up the Garmin to assume 200 gallons of useable fuel which should leave 5 gallons of prayer if I need it.
Luckly, my longest trip to date was about 240 miles round trip and I had plenty of gas left. I shouldn't have to worry about fuel unless I try to take two of these trips without filling up. If I do that I need to be shot anyway.
I consider those bars to be not much more use than the fuel gages on my other boats. They will only indicate "generaly", "about", "maybe" how much fuel you have.
