Small Engines (Lawn Mowers, etc.): Onan question, tractor engine, garden tractor

Question
I have a Onan 20T Garden Tractor Engine Model number is B48G-GA019.9/3713B. The engine will start but will only run on idle full choke, it will not run choke off or throttle advanced. Any advice would be appreciated.

Thank You
Rick

Answer
I would start by removeing, dis-assembling and cleaning the carburetor.  It sounds like there is major blockage in the main fuel circuit.  Taking your time while dis-assembling and coupling a digital camera photographing how the process will make re-assembling much eaiser.

Have the mowers carburetor ever been cleaned?  Is the air and fuel filter clean?
Let me know.
Eric