Small Engines (Lawn Mowers, etc.): briggs runs on half choke

Question
QUESTION: Model 303447 type 1222e1 code 01060111

Hi I've got a 16 horse briggs horizontal OHV on a Grasshopper.  About 900 hours on this engine.  Running fine yesterday, then noticed a loss of power which became worse rather quickly.  It starts fine on choke.  If the choke is taken off it dies.  Runs pretty well on half choke, sounds normal, no black smoke, doesn't seem to be either rich or lean at half choke.  Take the choke off and it dies seems like from lack of fuel.  I changed the fuel filter, that made no difference.  Any advice appreciated  Thanks  rick

ANSWER: I would start by removing, dis-assembling and cleaning the carburetor.  I would blow compressed air from an air compressor through all the carburetor orifices (holes).  Follow by spraying carburetor cleaner through orifices, then compressed air again.

Re-assemble, install and test.

Make sure you do not mess with the governor or the governor linkage.  Take pictures and mark the rods and rod locations so you know how to re-install.

Have you ever cleaned a carburetor before?  

Eric

---------- FOLLOW-UP ----------

QUESTION: hi  thanks for the answer.  I've done carburetors before.  I'm trying to understand what could be wrong with the carburetor.  The engine starts easily.  As long as the choke is on, it runs fine.  When the choke is opened it starves for fuel.  Close the choke and it recovers.I'm suspicious of the fuel shut off valve.  are those known to go bad?  Seems like that could cause this.  Is there a way to test it?  Thanks

Answer
You can use a 9 volt battery, or mower battery with clip leads to check the fuel shut-off solenoid.  They do fail once in a while but they usually prevent the engine from starting when they fail.

Search for fuel shut off solenoid and you will find several pages and You Tube videos on testing them.

http://www.youtube.com/watch?v=Kr6UayxyVwU


I suspect the carb is dirty.  Today's carbs are very sensitive, as they are precisely tuned to meet EPA requirements.  Our number one fix at the shop is cleaning carbs which is why I suggested you start with cleaning it.

Eric