I will tell you what has always worked for me. Get a clean clear plastic 8 or 12 oz soda bottle. Drill a hole in the cap big enough to accept the gas line that will be going into the fuel pump. Make sure the line fits tight enough in the cap so it doesn't leak. Fill bottle about 1/2 full of gas, push your gas line into the cap about 1/2 inch, push the other end onto your fuel pump. Turn the bottle upside down, so that the gas gravity feeds into the fuel pump. Let it sit there for a minute, then crank the motor. After the motor cranks about 5 seconds, start pumping the accelerator up and down, so the accelerator pump in the carb will squirt raw gas into the carb. DO NOT CRANK THE MOTOR FOR MORE THAN 30 SECONDS or you might burn up the starter. If it does not start on that first attempt, let the starter cool for about 5 minutes and then repeat the process. Once the car starts and runs, shut it off, take out your makeshift bottle set up off and connect the regular gas line.
You want to make sure the gas in the line and the tank is not contaminated before you do this. Hope this helps, it has always worked for me.