Fuel issues.......

First off, there are standpipes in your tanks (or pick ups that dont go all the way down). The bottom 10-15 gallons is never useable. That being said, think about the shape of your tank. If it uses fuel the level will drop form full quickly and gradually slow down as it gets to 1/2 (1/2 has the biggest area). It will then drop faster and faster untill your empty since the tank gets thinner and thinner. So, 3/4 is really 7/8thsish. 1/4 is really like 1/8th. 1/2 is 1/2.

 

I am not sure if tank straps were taken loose, to gain access to sending unit if so that could be it. It is along the theory that Richter explained only if the tank wasn't clocked the exact same the stand pipes may not be at the bottom of tank. Very little means a lot, that could also explain why the last 1/4 acts different. As he said though you will never use all the fuel, and the gauge will never be 100 percent. I keep mine clocked to where the tube isn't straight down. Water and trash settle in the true bottom, I like my suction line above that. Cleaner the fuel better your fuel system. Better the system less you spend.

 

I solved that problem by never running that low on fuel, when ya get to a 1/4 fill up, its a fairly simple fix

 

truck fuel gauge is our never wanna percent accurate. It is possible that sending unit was puttin backwards and maybe robbing the side of the tank when it goes down. also on my old Freightliner the fuel temperature sensor went bad and it was inaccurate it was always off by 20 or 30 gallons.

 

Mine does that. The volume from 1/2 to 1/4 is a lot more then the volume of 0-1/4.