Raoul,
You have a carb with a blocked passage in the body. You need to disassemble the entire carb and soak it in carb cleaner for a few hours, then rinse and blow out every passage. Then make sure every check ball is out of the carb and soak again,then clean and start reassembly.Take you time and check everything as you do it ,step by step.
When you are finished put some gas in the fuel bowl, with the carb fully assembled and open the throttle, you WILL see gas squirt down the center of the carb. If everything was cleaned and set correctly.
Like Steve_H said "it is not rocket science".
