Re: Riddle me this
 

Mine will show nearly empty and 15 gallons will take the gauge to full. I believe mine holds 27 gallons.

Due to no gas docks being open one May morming at the Lake of the Ozarks, I found out that I can go way past empty on my boat and still have gas.

I don't make a habit of it.

Re: Riddle me this
 

Sounds like me and you have the same issue. Let me know if you ever figure out what the problem is.

Re: Riddle me this
 

I'm not sure of the shape or position of your tank but my guess is that it is probably rectangular in shape and the vent tube is probably in the top rear of the tank. When the boat is sitting in the water and the bow is higher than the stern, the vent tube is probably covered by fuel when the fuel level is only partially full. The air trapped in the front of the tank prevents it from filling completely. If there is a threaded bung in the top front of the tank you may want to move the location of the vent to this spot
As far as the gage showing Empty when the tank still has fuel, all fuel systems are designed to do this. The question is; how much un-gagable fuel remains when the gage reads empty? The only way to know for sure is to completely empty the tank via the fuel pick up tube and note the position of the needle on the fuel gage with a piece of tape on the face of the gage when no more fuel can be withdrawn...this is true Empty.

Re: Riddle me this
 

I think the bottom line is these gauges aren't that accurate, all they can do is give you a rough idea of how much fuel you have.
I believe you can go way past empty in our boats, but I'm not going to chance it.