Small Engines (Lawn Mowers, etc.): Lawnmower engine surging/fading, sears craftman, internal passages

Question
Hi!

My mower runs but tends to surge and fade, but not stall.
Could this be a gas line or does it just need a good tune-up?
Its a 2 year old, 6hp, sears craftman.

Answer
If the carb is clean, it should just need an adjustment.  If the carb has a high speed mixture screw for adjustment, you should open it until it runs smoothly, then open it another 1/8 turn.  If it has no adjustment, this indicates there is a blockage inside the carb.  You would need to thoroughly clean the carb, including pushing a piece of tag wire through all of the internal passages.  Hope this helps.