The pressure and return lines are different sizes, so it is not possible to misroute the stock fuel lines. Having said that, the schrader valve is on the pressure line unless someone seriously mangled the fuel line plumbing.
uh oh then thats probably wat happened, bought the car like that, n the schrader valve is on the return line... oh well, ill just have 2 switch em around, they actually look the same size...both are 5/16 steel tubing