No Fuel

The drivetrain is complete (for now) and I am attempting to do the bodywork on my 67 myself in my garage. The problem I am having is that every weekend when I go to pull the car out of the garage I have to spray starter fluid in the carb to get it going. I can see through the clear fuel filter that there is no fuel in the line, but where is it going?? There is no leaks in the braided line from the fuel pump to the carb. There is no leak at the fuel pump either. I can go out to the car hours later and it will start up fine it is a gradual drain down. The only thing I can think of is that since the gas cap does not seal as it should there is no vacuum to keep the gas in the lines? :shrug:
 
I can think of 3 things that would cause bleed down, 1 would be that your gas cap is not venting or if you have a vapor can that is cloged. test your cap by running the engine for a while then shut it off and remove the gas cap slowly, if you hear air being sucked in then your cap is bad or the vapor system is cloged. I dont remember if a 67 had a vapor can or not. the next would be if the fuel pump has a internal leak but I would bet that your tank has a vacuum.