[Scott]

Whats the shape of the tank ...and does it happen when running or do you get the error when the boat is standing still?? If it’s a rectangle and the unit is mounted more towards the front of the tank all the fuel will “run” from the sender when under way ….but I doubt that’s the case with your tank….they are usually in the midsection
What did SPtanks say about it ?? you might just have a bad sender/bad connection … Does the sender have a mechanical read on the sender itself and if it does …does it read the same as your electronic gauge??? You could also pull the sender and measure its resistance to see if its faulty…for that matter pull it and swing the float up and down to see if the gauge moves on your console …..

Those guys at SP showed me a new sender ( I think magnetic) that looked really nice .... but more expensive....no float like the typical sending unit ... and to install you need clearance above the tank equal to the length of this sending unit... they made it out to be a very reliable sender ....Who knows....