I pulled my tank on my cyclone 4012 last weekend because of some fuel pump issues... My unit would run empty after using 20 gallons, put 20 gallons back in fuel would come out of filler neck.. 20 gallon tank right.....gauge never shows full or empty always between 3/4 and full or right at 1/4 when empty... Ok when I drained the tank before removing it I filled 5-5gallon cans and 1- 2 1/2 gallon can.. 27 1/2 gallons, So it's got to be a 30 gallon tank. The fuel pick/up's on these tanks is a plastic tube with a spring inside to keep it from collapsing and a screen on the end to keep the trash out..my guess is that the tube is curling up or resting on the raised part of the tank that runs the length of the tank not letting it get to the botton 10 gallons..Now to the fuel gauge, it stops about 2 1/2 inches from the bottom of tank not sure how or if you can make anykind of adjustments to that sending unit. But i would really like to figure out a way to fix that issue.. the fuel pick/up was a easy fix, take the spring out and replace it with a piece of steel fuel line,or pvc to make the pick/up more rigid, leave the plastic tube factory length but cut the inner tubing shorter so it won't bind up when the tank expands or contracts, it is a plastic tank The fuel station and the generator pick/up are the same style setups ( 1 for the gen. and 1 for the pump staion.. 2 total pick/ups ) My guess is the floating pick/up is to keep from picking up trash from bottom of tank . I hope this helps you understand whats going on in your tank.