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My mower listed above just started to run funny. It is hard to describe the sound of the engine in type but it goes up and down. Like pulses. Sounds like the engine runs up then goes back down. This is constantly while I'm mowing. Never used to do that. I thought it was not getting enough air, maybe filter clogged but I took the air filter completely off and it got worse. Any help would be appreciated.

pjc said:

My mower listed above just started to run funny. It is hard to describe the sound of the engine in type but it goes up and down. Like pulses. Sounds like the engine runs up then goes back down. This is constantly while I'm mowing. Never used to do that. I thought it was not getting enough air, maybe filter clogged but I took the air filter completely off and it got worse. Any help would be appreciated.

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Yeah, it sounds like the engine isn't running at it's full power (like it is idling or something). I don't know what could cause that, though.

Just the fact that it ran worse with the air filter off tells me that it is starving for fuel. Drop the float bowl and run a tag wire up the center into the main jet, then shoot some carb spray up into it and you will see the spray exiting into the throat of the carb.

When an engine like this hunts and does not run at a steady speed, it's generally due to a fuel delivery issue, typically debris or gunk blocking fuel in the carburetor. A complete and precise cleaning of the carb and installation of new gaskets would probably resolve the issue. Sometimes, it's even cheaper just to replace the carb outright.

I posted a how-to guide on another site; look here for the details:

How To Clean a Honda Carburetor - Lawn Mower Forums : Lawnmower Reviews, Repair, Pricing and Discussion Forum

pjc said:

My mower listed above just started to run funny. It is hard to describe the sound of the engine in type but it goes up and down. Like pulses. Sounds like the engine runs up then goes back down. This is constantly while I'm mowing. Never used to do that. I thought it was not getting enough air, maybe filter clogged but I took the air filter completely off and it got worse. Any help would be appreciated.

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This is an indication that excessive air is being introduced. Ensure the crankcase hose is not cracked and attached correctly. If equipped with a primer bulb ensure it isn't cracked. Check all hose clamp areas for cracked line. Does the choke operate freely? All bail handles working properly? All wire cables attached correctly and operating? Springs on carb attached correctly?