[Lynn Eades]

You dont give us much to go on.
What was it going like before you changed the dizzy?
Remove the pipe from the carb. Crank her over and see if you get fuel. Is there enough? Remove the pick up pipe from the tank. Make sure its filter is clean. (is the pick up pipe rusted through or the solder cracked) Use a vacuum / pressure gauge on the pump. It should deliver about 2 to 2 1/2 lbs of pressure (delivery) and should hold a vacuum of about 15 (inches of mercury) (suction side) Make sure there are no air leaks anywhere on the suction side of the pump. The easiest way is to connect an alternative line to the pump. Note; fuel change over taps are notorious for leaking air.
If all of that checks out then maybe you have a carb problem, but I would still think about the dizzy. Even new condensors can be faulty.