Puffs black smoke when full throttle mowing

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Firefighter_16

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Hello, i have a 2020 bad boy magnum with 56hrs on it. When im mowing at full throttle it starts to bog down and puff black smoke. If i back off the throttle just a little it runs perfect. I had it in the shop to get serviced. Oil, filter, fuel filter, new fuel pump, air filter cleaned. Still doing it. Any suggestions on what it could be? I run new premium gas in it every fill up.
 
Black smoke indicates unburnt fuel, it's flooding at full throttle it seems - not sure if there's a " high speed " adjustment on the carb or not but that's where I'd start. I'd try it without the air filter and see how it does - too much fuel is the same as too little air flow.
 
Bertrrr said:
Black smoke indicates unburnt fuel, it's flooding at full throttle it seems - not sure if there's a " high speed " adjustment on the carb or not but that's where I'd start. I'd try it without the air filter and see how it does - too much fuel is the same as too little air flow.
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Im not sure if there is a high speed adjustment. But i will try without air filter and see what happens.
 
trying without the air filter only risks damage to the engine. The problem is too much fuel. That is either a dirty air filter, or too much fuel for the load and RPM. If the air filter is clean then it is too much fuel - a high speed adjustment. That said, if it is unadjustable then it may be a design problem and others will end up with it too. Check to see if the air cleaner is clean.
 
sgkent said:
trying without the air filter only risks damage to the engine. The problem is too much fuel. That is either a dirty air filter, or too much fuel for the load and RPM. If the air filter is clean then it is too much fuel - a high speed adjustment. That said, if it is unadjustable then it may be a design problem and others will end up with it too. Check to see if the air cleaner is clean.
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The shop i had it in said they cleaned the air filter. I dont know if its adjustable or not. How do i tell?
 
Any adjustment on the carb will be a slotted screw with a spring behind it for tension, these days most do not have any adjustment, you can run it without an air filter for a few minutes just for trouble shooting purposes without doing any damage. It's an easy test and only takes a few minutes , I don't trust anything a shop tells me any longer
 
Bertrrr said:
Any adjustment on the carb will be a slotted screw with a spring behind it for tension, these days most do not have any adjustment, you can run it without an air filter for a few minutes just for trouble shooting purposes without doing any damage. It's an easy test and only takes a few minutes , I don't trust anything a shop tells me any longer
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You can certainly run it safely for a short time in a controlled dust-free environment like your garage. You wouldn't want to run without the filter while mowing through, because it could pull in dust & dirt instantly.
 
You might even try looking at a engine IPL of the carb type.
If the choke is not a separate cable the throttle cable is adjusted wrong.
Post up some engine ID info and maybe we might see something on a IPL?
 
If your carb has jets that are held in by an O ring then you get a similar set of symptoms if the O ring is cracks, broken or loose as fuel can get sucked both through the main jet hole and around the outside of the jet itself and you do not need much of a leak to make it run rich .
 
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