Small Engines (Lawn Mowers, etc.): B&S Armature magneto 691060, carburetor issues, use of ethanol

Question

magneto B&S 24 hp Intek engine 9445677-0413-e1) on 2004 sears dty 4000 has started popping and backfiring; when mower deck in use not as bad.  New plugs; changed oil/filter; new air filter.  Any ideas? How can you tell if magneto is bad?

thank you

Answer
I doubt you have a bad armature. This is probably a carburetor problem. There have been a lot more carburetor issues since the government has mandated the use of ethanol in our fuel. I suggest removing the carburetor, and cleaning it thouroughly and replace the fuel filter and that should fix your problem.