Honda lawn mower running poorly


  #1  
Old 03-26-20, 10:56 AM
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Honda lawn mower running poorly

Mower is about 4 years old, always garaged.

When we went to cut the grass the other day for the first time this spring, the mower started right up, ran ok for a minute or so, then starting slowing down as if it were running out of gas. It would hang out with a very low idle, almost dying but not quite, then eventually rev back up again for a minute or two before slowing down again and repeating the cycle.

I replaced the spark plug with the properly gapped Honda plug, replaced the air filter, and made sure oil level was normal. No change.

Gas was probably 3 or 4 months old, but nothing different than any other season.

Suggestions for most likely cause?

Bad gas? Blocked gas cap vent? Fuel filter? Gunked up carb jet? Other?
 
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Old 03-26-20, 11:03 AM
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Is it puffing black smoke when it's sputtering? If so, the choke is staying on. If not, the carburetor probably needs cleaning.
 
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Old 03-26-20, 11:32 AM
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All of the above, but I'm betting the Carb as Cheese is suggesting.
Try removing the carb. But before doing a tear down, use an air compressor and blow out all the orifices. Lately I've been very successful with that method.
 
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Old 03-26-20, 01:29 PM
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No black smoke of any kind when running, no sputtering or knocking, just sounds like it's running out of gas before reving back up again. I usually run the tank empty and leave it that way over the winter season but didn't this time. Any possibility there has been some condensation and there is some water in the tank, or is that far fetched?
 
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Old 03-27-20, 04:59 AM
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Contaminated fuel is always a possibility if you've let the machine sit for months. Condensation isn't much an issue if you completely filled the fuel tank before putting it away for the winter but if the tank was only partially full then it will "breathe" with every change in temperature or air pressure and bring in fresh, humid air that can condense when it gets cold. You can remove the fuel line and run fuel into a container and see if there is water if you are running alcohol free gasoline. If you are using a fuel that contains alcohol then the fuel itself can absorb moisture/water without it forming separate water droplets.
 
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Old 03-27-20, 07:16 AM
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Drain old gas and refill with fresh fuel and add a strong dose of SeaFoam it will probably clear itself . Have a good one. Geo
 
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Old 03-28-20, 02:10 PM
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Drained fuel line and carb bowl, emptied gas tank and dried it best I could with clean rag, made sure vent holes on gas cap were open, and put fresh gas in it. It ran fine without stalling or hesitating at all. Still doesn't seem to be operating at full power, but got the job done. I'm hoping as I work through a couple of tanks of fresh gas it will improve. If not, I'll be back. Thank you all.
 
 

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