Can't Get Fuel To The Holley Red

I installed my electric pump (Holley Red) with a filter between it and the tank, then 3/8 line to the carb with another filter in between. I cant get the pump to draw from the tank of my 69 Barracuda. Thought it might be the pump but it will suck fine from a jerry can, so i know its not the pump. The line (rubber fuel line) is clear from the tank to the pump. I know the tank itself is clean inside but took out the float unit, checked it over and put it back in months ago prior to putting the tank back in. Does anybody have any idea what could be wrong inside the tank? Is there anything that can go wrong in the tank float unit? Thought I would ask prior to draining and dropping the tank back out. Thanks for your help.