So after tuning my 09 f350 is always running on fumes at around 100 miles dte. I have actually ran it out twice now because I was never informed this would occur. I spoke with another 6.4 owner with the same setup and he said he never gets below half in his becuase his is the same way. I have researched a little but haven't found a solid answer. What is the cause of this? Is there a solution? And does everyones truck do this after tuning? Its not a huge deal, just remember to stop at 3/8 of a tank to be safe, but something still is not right.