I have a Husqvarna tractor that has a B & S Vanguard 21 hp on it that is about 4 years old now. It will run fine for a short period then start spitting and sputtering to a point that it almost dies when the blades are engaged. It usually runs good just driving. I have done all the normal maintenance work (changed oil, spark plugs, air and fuel filters…). Not sure where to go from here. The spark plugs are a dry black.

There is black smoke when it starts to sputter. Also, ever once in a while when going up an incline it will spit out this black smoke. Other then that it drives fine with the blades turned off.

Walt Conner

Alternately disconnect & ground one spark plug wire and see if one cylinder is noticeably weaker than the other.

If needed the label also has a tag labeled Type: 0349-E1 and another label CODE: 04042811

The problem does go away for a short time after the filter is cleaned really well or replaced but this can not be the only problem because I am cleaning the filter ever hr or so just to keep it running and this is a new filter (4-5hrs old). It is a little wet.

Could it be the valves? What should they be set at??

What should they be set at?