Small Engines (Lawn Mowers, etc.): B&S model 98902 will not idle

Question
I have a power lawn trimmer with a B&S 98902 - 1110B1 engine.  The engine starts and runs but will not idle, instead it revs up and down.  I'm not sure where to start looking for a solution.

Thanks

Answer
Almost all surging problems are caused by a dirty carburetor.

Have you removed, disassembled and cleaned the carburetor with compressed air from an air compressor?  I would use spray can carburetor cleaner as well and spray carburetor cleaner through all the carburetor orifices to make sure they are clean.

If you have never cleaned a small engine carburetor you can view lots of videos on You Tube on how to clean and overhaul small engine carburetors.

Eric