Small Engines (Lawn Mowers, etc.): weed wacker, spark arrestor, couple seconds

Question
I have a cub cadet cc4065 weed waker. i can sometimes get it to start, when i get it started it runs great for a couple seconds then it dies out and i cant get it started again, and when i do get it started it blows a grayish white smoke out of the exhaust. What does this mean? is it fuel related?

Answer
Have you checked the engine oil, the muffler spark arrestor screen and the air filter?  When was the last time you replaced the spark plug?

How old is the trimmer?  Did you check the service manual, the section covering valve clerance adjustment?

Manual link:

http://dl.owneriq.net/5/585324dd-c608-3444-710e-dc22bc0752bd.pdf

Let me know.
Eric