gas tank sending unit on 99 Sport?

I recently sold my 88 2001 and purchased a 99 Sport Nautique. The sport with the GT-40 seems to use more fuel than my old boat. The fuel gauge, however, just doesn't seem correct to me. The boat has a 30 gallon tank according to the specs. However, I can have a near empty tank, according to the gauge, and it will only take 12-15 gallons to fill it up. I haven't run the gauge fully down to empty because I do not want to be towed back to the dock. Is there an easy way to visually check the tank on the Sport Nautique? I am thinking that maybe the sending unit in the tank is bad?

The older style senders, which you probably have, have a float on the end of a thin metal rod. Kind I'd like an older style toilet tank.

If this rod was bent up too much, or (cut) too short, you'd get an empty reading too soon.

Thanks. I think I will pull the back seat out for a closer look and swap out the sending unit.

I rebuilt my original unit, but it did not have a float issue, just a broken resistor wire. In your case if the float is waterlogged a bit it will register low. They are adjustable. You can slide the rod in and out to adjust the reading. At least you can on my 78. Try extending the rod....

C-Bass wrote: On our 99 you can see about a 1" wide section of the tank from top to bottom if you just open the trunk and take a look. Keep in mind that the upper half of the tank is much thinner than the bottom (since it is "L" shaped under the rear seat).

Ditto for the 2000 Sport. You don't have a problem with the sending unit. The problem is with the design of the shape of the gas tank.