I have a clear filter that stays empty(97% of the time) while driving or idling.It doesn't seem to affect horsepower,but I know this is not right.I have new fuel pump,replaced lines,new carb,and replaced tank a year ago.Truck is drove no further than walking distance back home,so I don't know any long distance affects.

 

Mine is full when cold, then is pretty much empty most of the time. It has never effected anything on mine.