Small Engines (Lawn Mowers, etc.): lawnmower wont start, hi tim, debris

Question
Hi,
My push lawnmower with a 4.0hp B&S engine won't turn over. It sounds like it wants to start but backfires and dies. It isn't that old but hasn't had any maintenance so I was thinking it might be a dirty carb or something. I did notice that the throttle doesn't really do anything when you slide the lever from side to side. Looks like the springs are loose or something. Could that be the issue? I'd like to try to fix it myself so anything you might be able to tell me to narrow down the problem would be helpful. Thanks,
Tim

Answer
Hi Tim,

It might be a dirty carb or a timing issue.  The throttle should be okay.
Try to start the engine while squirting fuel or starting fluid into the carb intake.  If it starts and you can keep it running by adding fuel, then the carb most likely has dirt, debris or gummed fuel inside.
You will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air.   Probe each and every hole with a small wire.   A carb rebuild kit wouldn't hurt either.  

Let me know how you make out.
Michael