Sometimes the fuel pressure from the pump will push open the needle and flood the
carb. On Mikuni carbs they sell needle and seats with a smaller hole for use with fuel pumps but with a stock tec
carb your out of luck. You could try to lower the float a bit but the best bet is to use a bypass back to the tank. It is done on shifter karts all the time. You plumb a Y connector into the pump output going to the
carb and a return line back to the tank. You may need a restrictor in the line back to the tank if you do not get enough feed to the carb.