SO 37.1 Fuel tank

[tbetts007]

Hello, I have an 1994 SO 37.1 with an 37 gallon fuel tank. I've had it about 3 years. The fuel gauge has never worked correctly so I monitor the hours I use the engine carefully. By all indications, I ran out of fuel the other day even though, by my calculations, I should have had at least half a tank left. I figured blockage at first, changed filters, tried to bleed lines, but just got air. Finally, as a last resort, I filled it with fuel, bled the lines and it started right away and has run perfectly since then. The odd part is that it took only 18 gallons to fill the tank. Since then I've put on around 10 hours on the engine which should have used 8 to 10 gallons of fuel. I got around to fixing the fuel gauge yesterday (it always reads full) and when I pulled the sending unit, which checked out good, I noticed the fuel was to the top as if I hadn't used any.
I can't for the life of me., come up with a plausible explanation.
Is it possible that the tank is so full of sludge that it's blocking fuel flow through the baffles in the tank? Is this even possible?
Any suggestions?

Terry

[Zanshin]

How is the fuel pickup and return plumbed in to your tank, could that have gotten loose and is now sucking in fuel from mid-tank?
I would think that if the fuel tank were that dirty then your filter would look black and putting in extra fuel wouldn't increas the pressure enough to make the system work.