I put Seafoam in the unit, and it helped the unit, but it still surged. In it went to the dealer and they said the carburetor was bad and needed replacing. The did replace it, to the tune of $107, and charged me only for the part, and waived the labor charge.
I used SeaFoam in my Honda generator and had to have the carb cleaned. I think SeaFoam works too well and all the little dirt and crud in the gas tank gets cleaned out and goes right into the carb. The jets in the carb get plugged. Blow the jets and passageways out with compressed air and use some carb cleaner after using SeaFoam on an older generator and it should good to go.