I swapped from tpi to carb setup. I have a 305 motor. I changed the tpi pump to a tbi pump. I am running a mallory fuel pressure regulator. My question is why do I have to use a pressure regulator (cheap one from advance) on my return line. If I take the return line regulator off. My fuel pressure gauge maxis out at the highest reading. Anyway to fix that? Thanks for the help

 

You don't - whoever told you that was wrong!

All you need is the Mallory regulator, nothing else. Your pressure is maxed out because the el cheapo pressure regulator is restricting the return line - remove it!

Feed line goes into side of Mallory, return line goes in the bottom of Mallory, line to carb goes in other side of Mallory - done. Feed loine is the 3/8 line, return is the 5/16 line. If using hose barbs, make sure you don't try to shove a 3/8 barb into the 5/16 hose - it'll cut the rubber inside the hoise and cause yet another restriction.