Rodd
Recruit
Thanks. If this doesn't work I'll check the orings on the FSU.Air in the fuel would cause stuttering and smoke. Address the loose stepper motor. If that does not clean it up, then you will need to address potential air leaks on the the suction side between the fuel tank and lift pump. My recent experience has been the o-ring seals are where the hard lines connect to the sender particularly with the age of the truck. Good news a new set of seals is less than $10 at Napa. Bad news, you get to drop the tank.