Originally Posted by Travis Followell
Your carburetor needs to be cleaned. take the carb off and take it apart, spray with carb cleaner and blow it out with compressed air. If the engine is very old or the parts in the carb look pretty bad then you will want to go ahead and get a rebuild kit for it. Will cost you around $20-$25 for the kit.
This is true. What is actually wrong is there is something plugging your main jet. Maybe a piece of trash or even water. Anytime you see an engine that will only run on choke, the carb almost always needs to be cleaned. The only exception is an insufficient fuel supply problem. What is happening is the carb is being forced to draw fuel from a place it should not normally have to.
However, cleaning carbs correctly is not for an inexperienced beginner. If you have not had any proper training, you'd be much better off taking it to a shop. It's much cheaper to pay them to do the job right than to buy a new carb because you broke something which is very easy for an untrained person to do and not even know it. I fix problems like this all the time at my shop when I could have fixed it cheaper if the customer would not have "fixed" it first.