if i go from the metal supply in the engine bay to the sight glass to the ip = no air,...
if i go from a gas can to the filter to the sight glass to the ip = no air bubbles,...
if i go from metal tank supply line to filter to glass to ip = tons of air bubbles,...
the only thing i could figure was a vent or screen blockage that creating extra suction pressure from the tank that caused the filter to draw in air .?.?.?.
Is there a vent? where is it ?