Small Engine Troubleshooting Problems? Ask a Mechanic Now.
It is running lean, try removing the nut on the bottom in the center of the carburetor and cleaning the holes in it very carefully. If that does not work the carb will have to come off, be dissembled soaked in good (NAPA) carb cleaner for several hours and the a new carb kit installed. Make sure to diagram all linkage and internal parts so reassembly is proper.