air in fuel

[genchowford]

92 f350 7.3, every so often have to bleed the schrader valve, has holley blue mounted just after the pollack, mechanical pump disabled, have checked all the connections. any help would be appreciated.
thanks
Fred

 

[NCheek]

When was the last time the return lines were replaced? 95% of air problems are in the return lines, so I would look at them first.