Small Engines (Lawn Mowers, etc.): Air Filter on Mastercraft Lawnmower, speed jet, lawnmower

Question
I have an older Mastercraft Lawnmower (I am unsure of the
specifics) that has a problem.  Although it starts, it quickly dies
off.  

I have found that the lawnmower starts and stays running
perfectly if I remove the air filter, but dies as soon as the air
filter is put back into place.  

The air filter was dirty, so I bought a new one.  Unfortunately we
still have the same problem.  It runs fine without the new filter
on, but as soon as we put the filter back in place the mower
sputters out.

Any help here would be greatly appreciated.

Thanks


Jim

Answer
Hi Jim,

With the air filter installed a choking effect takes place.  I would suspect that the carb is allowing too much fuel to enter.  With the restriction of the air filter, the mixture is rich and out of balance.  Try adjusting the carb (If adjustable) by slightly closing the high speed jet.  If that doesn't help I would check the float for a level setting and the needle and seat for debris or leaking.   

Let me know how you make out.
Michael