Small Engines (Lawn Mowers, etc.): Weed Eater Leaf Blower, walbro carburetor, air leak

Question
I have a Weed Eater Leaf Blower Model BV1650.  Ran fine then all of a sudden stopped.  I cleaned the fuel tank filter and check it; you can suck air through it.  I have replaced the fuel supply hose and then replaced the Walbro carburetor.  Spark is strong and compression is over 90 PSI.  I can get it started but it will only stay running for 30 to 60 seconds and will not take any throttle.  I have tried running it with and without the muffler.  I have heated the muffler to cherry red to make sure it was not blocked with carbon.  The piston looks in fairly good shape through the exhaust port.  No major scratches.  No adjustment to the carburetor seems to make a difference.  What next?

Answer
Crankcase air leak?  When you replaced the carburetor did the carburetor gasket line up with the carburetor pulse hole?


The rear crankcase cover has an o-ring to seal the crankcase.  I have had these o-ring leak causing problems like yours.  Remove the cover, clean the o-ring, housing and crankcase with brake cleaner.  Use Permatex 3 non-harding gasket sealer and apply a bead on the o-ring and then re-assemble.

Let me know if this fixes your problem.
Eric