There could be a port somewhere in the carb that is plugged with trash. I go through this occasionally, especially check the carb throat carefully as these things can be very small and can drive you nuts finding them and getting them cleaned out. I use cutting torch tip cleaning wires to rod out the ports, they come in a plastic or aluminum case with various size wires and are handy for this job. If your cart is going to sit for any length of time, shut the gas off and run the motor til it dies, I have found this EPA gas raises hell with small carbs if they sit idle for any length of time. Hope this helps.