Having gone through fuel drama recently, I would suggest going through the process of elimination to get to the root cause. It could be the screen in the carb, your pump, older rubber lines, crimped metal fuel line or as Aus stated, the sock in the fuel tank is clogged.
After checking for obvious line issues (cracks and crimps and the screen in the carb), this is what helped me and what I wished I started with: "ALPHA MOTO Motorcycle Shop Auxiliary Gas Fuel Tank" -- Purchased on Amazon ($40?) and its essentially an IV drip bag for your carburetor. It removes the pump, lines and fuel tank from the equation. Just the external fuel tank (hanging from a stand like a hospital IV bag) and your carb. If your car won't run like this, it would suggest a carb issue. If it does, then you can start reconnecting fuel system components until you get to a failure point.
For example, if it runs off the fuel drip bag, then I would disconnect the fuel drip bag and (safely!) connect the fuel pump back up to the carb but connect the suction line that goes from the fuel pump to the tank into a small bottle with gas in it. This way you rule out if it's a pump issue or not. So on and so forth. Dropping the tank could be a pretty big PITA and it would be my last check.
Best of luck in your quest.
-Tony
