Originally Posted by snakebit68
Sounds like the fuel pump cam lobe. Of course, check the plunger rod first to eliminate that as a cause. They are a relatively simple set up, so it can only be one of those two things...unless you are misfortunate enough to have purchased that many defective fuel pumps...doubtful! Make sure your lines aren't run backwards somehow or you'll be trying to pump fuel out of the carb into the tank.
X2 on checking the lines are correct. My son and I did just that when firing up his 350. Stumped us for a few minutes!