Small Engines (Lawn Mowers, etc.): craftsman 4.5 wont start, carburator, dark smoke

Question
what do i do?
i changed the oil, i cleaned the spark plug. my mower will crank only for a few seconds , only if i prime about 10-15 times, then it will sputter and cut off. dark smoke will come out the moter after it runs about 20 sec, thats when it will cut off.

Answer
 Hello Sandra:

 It Sounds like the Carburator needs to be Cleaned and Rebuilt. It should Only take 3 or 4 times Pushing the Primer to Choke the Engine. The Running for a Few Seconds and Quits is a Good Indicator of the Carburator being Clogged with Trash/Water and Varnish that the Gas will Form Over Time. The Carburator should be Soaked Overnight in Cleaning Solution and then All the Ports and Passages Blown Out with Compressed Air. If you Wish to Attempt the Carburator Rebuild yourself, Send me the Make, Model, Type and Code Numbers Off of the Engine , Please. With these Numbers I May be Able to Locate a Breakdown that will Assist you in this Repair. Hope this Helps. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John