my mazda tribute 2002 does smoke black sometime and it burning a lot of fuel. Can anyone tell me what is cause that please?

The first thing I would have done is to check for code on the ECM. Could be burning rich to which extent your fuel trims are not correct. This could be caused by o2 sensors, idle air control valve, temperature sending sensor, mass air flow etc.... I would think your check engine light would be on. Other wise have a mechanic check over the cars readings while running with a scanner.