Why would a 1992 Mercury blow black smoke?

Black smoke is caused by an over rich mixture and normally occurs whenever the engine is working hard. Like going up a steep grade, being loaded heavy or during heavy acceleration. More black smoke can be observed when the vehicle is operated at higher altitudes because the air is thinner. A dirty air filter is also another cause of excessive black smoke. If black smoke is noticed while the engine is idling at low altitude or under normal driving conditions this condition should be diagnosed a.s.a.p. to prevent engine damage. bad rings or busted pisten you need anew motor