Here's one for ya. I have a 21'center console with a 48 gallon fuel tank. The guage shows full all the time. I pulled the sending unit out and moved the float up and down and the guage registers fine.I put the sending unit back in slowly moved it up and down and the unit and guage works fine. I screwed it back in(poly to poly) after checking for obstructions and it still registers full no matter what the level. Any suggestions? Thanks .......Wes