Having a fuel tank issue driver

Sounds like the fuel tank vent went bad, or clogged. They are not that expensive, replace them both.

 

Some trucks have their fuel return to the right side and equalize with the left.

 

It may be. I had the same issue, replaced both vents and it fixed my problem. Usually, the vent hose falls off and dirt and water gets in. You can never get all the dirt out, its best to replace them.

 

If you follow the fuel lines to where they all go into a block on top of tail end of trans. That block has a valve that keeps the fuel at same level in both tanks, it may need to be replaced?

 

Had a KW that did that to me once... Was a plugged return line to one tank. The inner lining of the fuel line had begun to deteriorate and some of it had flaked off and plugged the line.

 

Yes. I drove a western star that the right tank never would empty and the left tank would run lower after running it for a while. I actually ran out of fuel with that truck because I checked the right level on my Pretrip (habit when I was doing the temp driving) and on the way back to the foundry, I had to take another road which had an on-ramp on a hill with a light at the top, which exposed the fuel pickup in the left tank and sucking air waiting for the light to change. I made it off the ramp but stuck 150 feet after turning onto the road. The right tank was half full of fuel, and i had to sit there for an hour waiting for the fuel to equalize enough to get the left tank to cover the pickup tube.