Craftsman snowblower - runs rough (very rough) black smoke coming out of exhaust - thick oily soot like stuff inside exhaust and then stalls. Help? It is six years old.

Usually a bad ring or seal inside your engine allowing oil to get into the combustion chamber where the tip of the spark plug is located. Do you notice any smoke coming from the exhaust pipe ?? Do you seem to be adding oil more often ?? If so, the black oily stuff is "engine oil".

If gasoline is left sitting for a while (2-3 months) it attracts water, which could cause the "smoke" and rough running engine.
Unless it is a 2 stroke engine, no oil should be coming out the exhaust. Hold a clean rag or a bunch of paper towels at the exhaust opening BE CAREFUL NOT TO BURN YOURSELF and than check if, whatever the rag or paper towels catch is oily. If it is a 4 stroke engine, and oil is the exhaust fumes, a seal inside the engine is gone and has to be replaced.

white smoke is more than likely a water issue. Oil usually has a bluish tinge to it but is some cases, it could be white. Drain the gas a fill with fresh to try and eliminate the possibility of water in the gas. Watch the oil level to see if it changes after using the mower. it may take a few times but if it is burning oil, the spark plug will look "wet" and oil soaked, with possible black soot type build up.

sounds like you are burning coolant. sounds like you have a headgasket issue or cracked block. is your coolant level low?? in the overflow bottle and in the raadiator? something tells me that you will find that coolant is low. you are pulling coolant into the engine and it goes into the cylinder and pass the exhaust to the back of the car. the white smoke is the coolant burning off and thats why the car runs rough, because coolant is not flamable so it doesnt burn. this results in the spark plug not firing right and having rough running condition.

signs of a bad fuel pressure regulator-- the vehicle will run rough, the engine will not start ( usually in the mornings,) many times engine starts but stalls shortly after starting. a bad regulator can result in fouled plugs. replacement is only cure. 1- black soot on plugs-2-black smoke from tailpipe-3- running rough-4- stalling, good-day! repost if need be.

Exhaust problems. Black smoke=exhaust, blue smoke=oil, white smoke=water.

a bad fuel pressure regulator causes this. black soot on plugs, black smoke from tailpipe, running rough, stalling. first check plugs and wires.

possible check vacume hoses if its hookup properlly

carb automatic choke sticking closed or your float setting too high causing flooding engine.

you have a blown head gasket you need to get it to a shop as soon as you can