high wing fuel flow

[bobnoffs]

was hanging around the fbo yesterday wasting his time with several other pilots and one mentioned that his wing tanks don't drain at the same rate [zenith]. they are plumbed together and i can't formulate a reason why this is so. one said the venting and another said the fuel lines. as both the vents and the fuel lines could accommodate a fuel flow several times more i can't see how they are a factor.
anyone have a theory?

[RONSIM]

on high=wing Cessnas ---- had a few ----- venting, out of rig, etc. ----- my 182s never flowed evenly --- my hangar neighbor just built a Highlander STOL-----same issue.