Lawn Tractor Question

I took off the carb and sprayed carb cleaner all through the insides of the carb. The carb appears visually to be as clean as it can get. I still do not understand what is going on with this. It does not have a fuel pump. Just a tank with a line and filter going to the carb. And as stated before, I can pull the hose at the carb and gas is pouring out the end of the hose. I will try one more thing. I am going to drain out ALL the fuel and put in new fuel and try to get it running. That's what the lawn mower repair shop just told me to do when I called them.