Mower Only Runs Well On Choke (Lopey Idle)

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gathermewool

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Having issues with a very lopey/rough-running mower. Looking for some help.

Mower:
Cub Cadet CC550

Issue:
Before the tear-down, the mower only ran on choke. Even after it was warmed up, it would stall almost immediately when the choke was released.

Maintenance:
1. Drained all fuel
2. Cleaned carb (looked pretty good)
3. Replaced fuel and air filters
4. Replaced spark plug
5. Replaced gasket
6. Added Berryman's B12
7. Added fresh fuel (just purchased today)

Result:
Now, it stalled when the choke was released, until warmed up. When warmed-up, it will run off-choke, but it's VERY lopey. See video below

Previous thread: New To Me Cub Cadet CC550 - Maintenance Tips

Video:
 
If it only runs with the choke on, its running lean. You might have to look really close at the carb and make sure all the fuel passageways are clear. One tiny piece of dirt is all it takes.
 
Last edited:
clean, clean and reclean the carb until it runs well..sometimes it takes a few tries to get it right. Others may suggest saving the trouble and buying a cheap replacement carb..
 
I actually did purchase a rebuild kit AND a new carb. The new carb was the wrong one, so it can't be used.

I now have a carb cleaning brush kit. So, even though it looked clean, I'm going to pull it apart and run brushes through every orifice to see if that fixes it.
 
My friend completely disassembles little carbs and ALWAYS finds a crumb of yellowed plastic.
He claims it's always a chunk of tubing eaten away by ethanol.

His small engine gig is what he does well. People love him for it.
 
Interesting. It could be that I inadvertently introduced something during reassembly.

I'll pull it apart again soon and see what I find.
 
If it starts and runs and eventually runs even lopy without the choke, the I advise to keep dosing the gas with B 12. I've had B 12 fail to help immediately, I resolved to tear down the carb the following week end. Saturday came, and I gave it one last pull on the way to the bench. It lit first pull.
grin2.gif
 
The engine runs better with the choke partly on BECAUSE it's getting too much air with the choke all the way off. This is the classic dead giveaway sign of a fuel delivery problem. People on this forum always tell you to clean the carburetor but they don't tell you WHY.
 
Originally Posted By: das_peikko
The engine runs better with the choke partly on BECAUSE it's getting too much air with the choke all the way off. This is the classic dead giveaway sign of a fuel delivery problem. People on this forum always tell you to clean the carburetor but they don't tell you WHY.


xxch4osxx explained why.
 
You can try letting it set overnight after it runs with some berryman b-12 in the fuel. If it still runs the same, you will need to take the carb apart and clean it. Lots of jets and venturi holes in some. I had the same issue with a generator that sat for 3 years. I use small .014 stylets to clean the various jets and ports.
 
Thin wire in every jet, hole and gallery followed up with compressed air.

Do that and the carb will run fine provided you got the wire through all of the above.
 
Originally Posted By: HangFire
xxch4osxx explained why.


I read the post. He didn't say WHY the engine was running lean with the choke off.

It's because the engine is getting too much air for the amount of available fuel at the present time.
 
Originally Posted By: boraticus
Thin wire in every jet, hole and gallery followed up with compressed air.

Do that and the carb will run fine provided you got the wire through all of the above.


This, actually followed up with carb cleaner spray then compressed air.
 
Ok, so what's in the carb now is treated with B12. I'll try to run it for a while later (likely in a couple of days, after the snow storm headed our way passes!)

If improvement isn't noted, I'll pull the carb again and let it soak overnight. I'll then clean it with the brush kit I bought. Since there has been SOME improvement already, I'm hopeful that some more cleaning will bear fruit.

Thanks again for the help, guys. I wanted to make sure I wasn't missing something less obvious. Seems like the answer is to clean, clean, clean the carb.
 
Originally Posted By: ARB1977
Hit it with some Amsoil Power foam.


Which store is that sold in, again?
27.gif
 
Don't know how many times it's been said. Elixers don't clean carbs. Don't care what it's called, it won't do the job. It will clean your wallet out pretty good though.
 
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