Kohler backfiring at high spped

Been working on small engines all my life but this is got me stumped..working on a toro blower with 23 hp kohler command pro..this is what it does,..it starts good,runs good ..i let it warm up a bit but when i rev it up all the way..its ok for about 15 seconds then the throttle goes down a bit and it starts missing real bad like its going to blow up..Now..pay attention to what im going to say cause this is key.. so i shut it off and i can turn it back on to start the motor..like right away... and its ok..rev it up with the remote..same thing...ok for a bit then it does it again...you can shut it off right away then start it right away and its ok...rev it up...same thing..i replaced the coils..i replaced the electronic governor unit on the machine from another known good running motor..what is it??? it definitely electrical cause you can turn it off and turn it back on within seconds and its ok,,then you rev it up..same thing..im thinking the fuel solenoid cause that would make sense with shutting it off and turning it back on right away cause its hooked to the ignition switch..i checked it and its going back and forth but maybe its getting hot and going back into the carb and starving the main jet? partial chock seems to fix this...what is it??? remember..i can shut it off and turn it back on within 5 seconds and it runs good...you tell me and i can run this unit at say just over 3/4 throttle and runs great all day...just when you go full throttle then it starts to spit and sputter

Something floating around in the carb partially blocking the main jet will cause the same symptoms.

ILENGINE said:

Something floating around in the carb partially blocking the main jet will cause the same symptoms.

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well,the solenoid goes into the main jet.thats what im thinking that its defective even though it works on the bench..maybe goes back in when heated up

If a problem can be worked around by varying the throttle setting then the only cause is lack of fuel.
So some where from the tank outlet to the main jet inlet there is a fuel blockage.
If you want to rule out the shut off solenoid then replace it with a bolt.
Oddly ever we call them bowl nuts but I have never seen a bowl secured with a nut.
Pinch a fuel tank off something else and rig up a temp fuel supply then hook it in at the carb, and at the fuel pump to try & identify where the blockage is.

bertsmobile1 said:

If a problem can be worked around by varying the throttle setting then the only cause is lack of fuel.
So some where from the tank outlet to the main jet inlet there is a fuel blockage.
If you want to rule out the shut off solenoid then replace it with a bolt.
Oddly ever we call them bowl nuts but I have never seen a bowl secured with a nut.
Pinch a fuel tank off something else and rig up a temp fuel supply then hook it in at the carb, and at the fuel pump to try & identify where the blockage is.

Click to expand...

well,its a special solenoid that has a plate that bolts to the carb and the solenoid needle goes into the carb and is seals with a wide o ring so cant put a bolt in it

bertsmobile1 said:

If a problem can be worked around by varying the throttle setting then the only cause is lack of fuel.
So some where from the tank outlet to the main jet inlet there is a fuel blockage.
If you want to rule out the shut off solenoid then replace it with a bolt.
Oddly ever we call them bowl nuts but I have never seen a bowl secured with a nut.
Pinch a fuel tank off something else and rig up a temp fuel supply then hook it in at the carb, and at the fuel pump to try & identify where the blockage is.

Click to expand...

actually when it acts up,i turn the throttle right down using the remote and its still doing it at low speed ,only when i shut the motor off and then turn it right back on,it fixes it until i rev it again..have to shut it off then turn it back on for engine to not miss