I have a 2 year old Husqvarna riding mower with a Briggs and Stratton engine. It ran fine until a couple of weeks ago when the engine started running rough and black smoke came out of the front of the mower. Thinking that maybe diesel fuel was put in it, I drained the tank and put in new gas and ran it for about 15 minutes. That was not the cure. It still smokes and runs rough. The spark plug also gets fouled. What could be the cause of this problem?:)

Sounds like your float in the carb may be allowing too much gas, debris in the needle valve. Shut off the gas, remove the bowl and clean the needle valve and seat. Check the float for smooth operation and insure that it totally shuts off the flow of fuel when it is raised.

That's right, it sounds like you are putting too much fuel into the cylinders by flooding them to death.

My husqvarna lawn tractor won't start I can hear it clicking at the silnoid but won't turn over what would the problem be