My fd engine isn't returning fuel to the tank I have all new gas lines new tank and I have replaced the fuel pressure regulator and it still isn't returning I even hooked it up to a straight vacum sorce and it still doesn't open. Why?????

 

is the pump making enough pressure or flowing at all ? possible lines hooked up wrong ?

 

It was a lose fitting on my fuel cell was allowing it to suck air. Thanks for the reply