Black smoke is generally caused by incomplete combustion
, usually due to either overload, or compression
or air/fuel mixture problems.
The first & simplest thing to check for is an air inlet restriction such as from a plugged/dirtry air cleaner/filtre. Take off the air filter and make sure the intake port is clear. If the engine
still smokes with the port clear and the filter off, the problem is elsewhere.
See also a very old discussion “The Smoking Gun “
Interpreting Diesel Exhaust Smoke
Goto ➥ The Smoking Gun