Black smoke can be caused when there is an improper air to fuel ratio. The fuel does not burn completely and the partially burned particles are expelled in the exhaust. One of the most common causes of black smoke is an air inlet restriction. This can be anything from a plugged air cleaner, an intake hose collapsing or anything else causing an air flow problem even plugged exhaust. On automotive applications the airflow through a paper filter is sometimes restricted enough to cause black smoke especially on acceleration. K & N has developed an air filter that allows for excellent filtration as well as plenty of air flow. The filter is also recleanable and can be used up to 50,000 miles without having to be cleaned.
Injector malfunction is also a common cause for black smoke as is incorrect engine timing. Overfueling can also cause black smoke and is one of the reasons setting a fuel system above factory specifications is strongly discouraged. Internal injection pump problems can also result in black smoke.
Chicks Fan
June 2009