govt

I'm sure as prices increase, we will see more comments on how to increase mileage. I'm currently getting 12mpg city driving tooling around town. Also get 12mpg pulling my 9,000 lbs trailer. I would think if things were working right, I would see a difference in mileage when pulling so my quest to increase mpg has begun. I have changed the fuel filter, IAT and installed a K&N. Still at 12mpg. When I park the beast at night, I notice a hum coming from the tank area. Someone suggested I clean out the port on top of the tank, which I did and was clogged with dirt. Could I have a pressure problem if I hear a hum from the tank?