Lawnmower running a little rough.

[edweather1]

I have a Craftsman 21" AWD Model 247.379550 with a 196cc engine. Purchased in late '16. To be honest I have been really bad about maintenance. Besides decent gas, oil, and air filter, I didn't do anything. It has performed very well until this year. I noticed it was hiccuping a little one time, and the next time I tried to use it, it wouldn't start. I found out the spark plug had come loose. Besides being loose, it looked good, so I just tightened it, and the mower ran great again. The next time I used it it ran okay but just a little rough. I put fresh gas in, changed the fuel filter inside the fuel line (that was a pita,) and air filter, and checked the vent hole in the gas cap. It's still not running100%. I would give it 9/10. My friend told me that I might have damaged it when the spark plug was loose. In the engine maintenance section of the owner's manual it talks about a Carbon Canister Filter, but I don't know what that is. Where do I go from here? Any suggestions are greatly appreciated. Thanks

 

[BigCahuna]

If it were mine, I'd replace the spark plug and run some carb cleaner in the gas tank. Then run that gas until it was empty. Carb Cleaner does nothing sitting in the gas tank, it has to be run thru the carb.,,

 

[Nukeman7]

Some might call this product "snake oil", but it is a great OPE fuel system cleaner and works as advertised.

 

[edweather1]

If it were mine, I'd replace the spark plug and run some carb cleaner in the gas tank. Then run that gas until it was empty. Carb Cleaner does nothing sitting in the gas tank, it has to be run thru the carb.,,

Any carb cleaner recommendation?

 

[Tdbo]

Any carb cleaner recommendation?

I just dump some Techron in mine. Usually have some around the shed anyway for the vehicles.

 

[edweather1]

Some might call this product "snake oil", but it is a great OPE fuel system cleaner and works as advertised.

Thanks, I might give it a try. What does OPE stand for? Thanks

 

[dvblanch]

Have the same mower and it has always run extremely lean w the plastic carb.Regularly just give it a little dose of Seafoam and that apparently richens it up enough that I can stand to use it.

 

[Tdbo]

Thanks, I might give it a try. What does OPE stand for? Thanks.

I have some techron. How much would you put in a small mower tank? The bottle usually says it's good for 12 or 16 gallons.

OPE is Outdoor Power Equipment.
When I put some in one of the mowers or my tractor, I usually do 2 or 3 oz.

 

[edweather1]

I just dump some Techron in mine. Usually have some around the shed anyway for the vehicles.

I have some techron. Usually says on the bottle it's good for 12 gallons. How much would you put in a small mower tank?

 

[Hall]

OPE = outdoor power equipment

For the Techron, without knowing the size of the bottle, you'll have to do the math. For a 1/4-gallon fuel tank on a push mower, even 1 ounce would be a lot, but I always overdose with Techron anyway.

Some equipment have a separate piece of foam as part of the filter housing. That could be what it's referring to.

 

[BigCahuna]

Any carb cleaner recommendation?

I use the cheapest stuff I can find at the auto parts store. It's a lawnmower, not the space shuttle.,,

 

[97prizm]

I have a Craftsman 21" AWD Model 247.379550 with a 196cc engine. Purchased in late '16. To be honest I have been really bad about maintenance. Besides decent gas, oil, and air filter, I didn't do anything. It has performed very well until this year. I noticed it was hiccuping a little one time, and the next time I tried to use it, it wouldn't start. I found out the spark plug had come loose. Besides being loose, it looked good, so I just tightened it, and the mower ran great again. The next time I used it it ran okay but just a little rough. I put fresh gas in, changed the fuel filter inside the fuel line (that was a pita,) and air filter, and checked the vent hole in the gas cap. It's still not running100%. I would give it 9/10. My friend told me that I might have damaged it when the spark plug was loose. In the engine maintenance section of the owner's manual it talks about a Carbon Canister Filter, but I don't know what that is. Where do I go from here? Any suggestions are greatly appreciated. Thanks

New spark plug correctly gapped. Check to see if the carburetor bowl has white crusty build up. Then clean out the jets.

 

[Japanese]

Any carb cleaner recommendation?

Any carb cleaner would work. Use the cheapest one (Super Tech etc).

However, if the carb jets are plugged, you won't solve the problem until you put apart the carb, soak it overnight in gasoline (SeaFoam etc), and the blow through all holes and jets either with comp air or carb cleaner.

There is no carb that will automatically unplug itself just by putting some cleaners in the gas tank and not putting the carb itself apart.

 

[6.7 CTD]

I have a 20-year-old Craftsman 6.5hp self-propelled push mower that has seen better days (my dad gave it to me about 7 years ago). After running Seafoam through it, it runs extremely well. Prior to this, it would take several pulls to start and run poorly at times (replaced plug and air filter). I’m not one for additives, but I strongly believe in Seafoam for carbureted OPE. I also used to run Mobil 1 5w30 EP HM in it and now run HPL 5w30 PCMO, which I personally find humorous. The deck will probably rot before the engine gives up.

 

[wavinwayne]

I have personally experienced Seafoam smoothing out a rough running John Deere Z535M, so I'd give that a try.

 

[Japanese]

I found out the spark plug had come loose. Besides being loose, it looked good, so I just tightened it, and the mower ran great again. The next time I used it it ran okay but just a little rough.

While your spark plug was loose your engine was running lean (it was sucking air from around the plug thread) and lost some compression. The lean condition may increased the cylinder temp. and your piston rings may stuck in the piston grooves at that same time they may scratched the cylinder walls.
You can check that by opening the cylinder and inspecting it along with the piston and its rings.
Also make sure the spark plug thread is not stripped.