Small Engines (Lawn Mowers, etc.): Husqvarna rider w/B&S engine shuts down, husqvarna rider, briggs stratton

Question
Husqvarna riding mower has a 23 hp Briggs & Stratton Intek V-Twin engine. Runs somewhere between 15 mintues to an hour then abruptly hesitates/sputters and stops. Might be able to restart after a minute or two working the choke.  Then, might run short time (10-15 minutes) or longer (up to around 30-45 minutes) and shut down again.  Or, on the warm engine re-start engine will immediately cycle/hunt a few times then shut down. After engine has cooled, it easily starts and will run for another 30 minutes or so with no problem but then shuts down again.  Is something overheating, causing it to shut down? Thinking there might be a vapor lock, I've loosened/opened the gas cap a few times while mowing, but it will still shut down.  Also, in experimenting, I've set a concrete block on the seat and let it run with the blade on and it runs forever with no problem (I stopped in at 1-1/2 hours).  So, it seems the problem occurs only when the transmission is engaged (hydrostatic trans).  Any thoughts on what the problem could be. Does Husqvarna have a problem with some sort of switch or other component apart from the engine that would shut it down.  It has a new air filter, pre-cleaner, plugs, and fuel filter.  Shop tells me the engine, plugs, ignition coils, etc., check out OK and they can't get it to shut off for them (because they ain't riding it!).

B&S Intek V-Twin Engine Model:  445577,  Type: 0755E1, Code 061205Y-G

Thank you for your time -

Ron


Answer
These are the hardest problems to solve.  The problem could be some debris in the carb, warped intake flange, and I have even had a seat safety switch cause this problem...took me almost 2 weeks and mowing many lawns to duplicate the problem.

Did the shop check the intake, headbolts and carburetor bolts torque with a warm engine?  Did the check the valve clearance?

It is also possible that the fuel solenoid power or ground is not exaclty right causing the problem.  While the electrical issues are very, very rare, I would recommed dis-connecting each electrical connector, one at a time, and then re-connecting them.  Sometimes a little corrosion builds up and will increase resistance causing the problem.  As the eletrical components heat up the resistance increases.  Like a said, a long shot but worth trying.

Does the engine use or burn oil?  

Let me know.
Eric