Small Engines (Lawn Mowers, etc.): 12 hp B&S wont stay running, wheelhorse, fuel flow

Question
Hi, I have a 12 hp B&S  wheelhorse, model #104959
It was running great, I noticed the last time I used it it was bogging a little,  now it wont run unless the choke is on?  This came on all of a sudden, I checked the air filter and it is fine...
any help would be great    thanks

Answer
Hi Mike,

Your engine requiring choking, indicates a lack of fuel flow to the engine.  Try adjusting the carb's mixture screws, as follows:.  
The high speed mixture screw is initially set at 1 & 1/2 turns out.  Then adjust it to give good acceleration and top speed, while not closing the screw more than you need to.  The low speed mixture screw is set at 3/4 of a turn out.  Adjust that, to give a smooth idle.  The 3rd screw, the idle speed screw, is set to give a low idle speed without stalling.   
If no change, check the fuel filter and look for a good flow from the fuel tank.  Finally, the carb may have dirt blocking an internal opening.  You would 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.   Adding a carb rebuild kit wouldn't hurt either.  

Another possibility: Check the gas cap to make sure it is venting and not causing a vacuum in the tank.    

Let me know how you make out.
Michael