Spark plug or fuel issue on Wheel Horse 5500 generator

[Mr. T. Minnesota]

I am having trouble with a Wheel horse 5500 generator running consistently. It runs as if it is low on fuel but backfires and flames coming out of the muffler.
The carb is clean and fuel is available. Could this be a spark plug issue. Runs for a while and then stops and runs again. The generator is used intermittently and I do not believe the spark plug has ever been changed. Any and all input is appreciated.

 

[wore out]

I am having trouble with a Wheel horse 5500 generator running consistently. It runs as if it is low on fuel but backfires and flames coming out of the muffler.
The carb is clean and fuel is available. Could this be a spark plug issue. Runs for a while and then stops and runs again. The generator is used intermittently and I do not believe the spark plug has ever been changed. Any and all input is appreciated.

I'm thinking it may be Wheel HOUSE generator by Generac/Briggs & Stratton?
You don't have much to lose be trying a new sparkplug, a "bad" one can cause a variety of problems

If that doesn't help it could still be a lean condition caused by a vacuum leak or something you've missed that's restricting fuel flow to and through the carburetor.

More odd things could be a sticking valve, a broken valvespring or a loose valve seat (IF applicable to your engine.)

Just some random thoughts!