# Choke Issue



## James (Nov 13, 2018)

I bought a brand new cub cadet Snowblower. It’s a two stage 24” 208cc model 31AM6BSR596. I started it up following the procedure explained on the machine.

Primer 3x, Choke on, throttle full (rabbit symbol), pull start, move choke slowly to run.

The last step is one that I’m not sure is right. The choke has 4 settings , “choke” then two more settings and finally “Run”. As soon as it’s running I move the choke knob to the next setting. I’ve let it run for a few minutes to get it warm and try to turn the choke knob again toward run however in both the third setting and “Run” setting the engine sounds like it’s stalling. 

Is this normal? Does the choke have to get all the way to run? Should I do a different start up procedure? What could be the issue on a brand new machine ?

Any guidance here would be great. I’d really hate to have to lug this thing to a dealer considering I don’t have a truck to put it in. 

Thanks in advance for help!


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## UNDERTAKER (Dec 30, 2013)

*Let it run on the setting before it sounds like it is dying off 4 awhile. then move it down to the run spot and see what happens. I have no clue what engine is on that machine so I am going off of what I do on mine. then report back this problem that is presenting itself on to the masses at hand. k:k:k:k:k:*


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## JLawrence08648 (Jan 15, 2017)

The choke needs to be on when started, as the engine warms you turn the choke all the way to off or in stages dependent on the outside temperatures. If you can't do this, and it's an older machine, then generally the carb is dirty and needs to be cleaned. Since your machine is new, check to see if the gas is old or has water in it. I would drain the gas in a container then into a clear soda bottle. Check the clarity of the gas. If there is water in the gas it will sink to the bottom of the bottle. Then put fresh gas in the machine. If this does not solve the problem, buy Seafoam motor treatment. This is a fuel cleaner. Run it for 60 minutes. If this does not solve the problem, most of us would take the carb apart and spray carb cleaner in every hole. You may choose to do that or call the dealer.


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## Town (Jan 31, 2015)

POWERSHIFT93 said:


> *Let it run on the setting before it sounds like it is dying off 4 awhile. then move it down to the run spot and see what happens. I have no clue what engine is on that machine so I am going off of what I do on mine. then report back this problem that is presenting itself on to the masses at hand. k:k:k:k:k:*


+1 on that approach.


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## James (Nov 13, 2018)

So a dealer just got back to me and said a lot of new machines need to be adjusted for altitude and pressure. Anyone ever heard of this ?


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## russ01915 (Dec 18, 2013)

outside temperature plays a big part on choke settings. The colder it is, the more choke ( it needs to stay running). Listen to the motor and forget about the settings. If it bogs down, move the choke to where the engine runs smooth. It's more of an art than a science. 

1. first start: prime choke on start
2. let it run a few seconds listen to the motor. It mat start to chug a little and some blackish smoke from the exhaust, move choke to the next position. 
3. let it run a little more, listen to the engine if it running smooth leave it, if it starts to idle rough, move choke again

some machines due to cold temps need the choke partially close.

It may be that machine needs to run at the second choke setting at that outside temp range.


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## Motor City (Jan 6, 2014)

James said:


> So a dealer just got back to me and said a lot of new machines need to be adjusted for altitude and pressure. Anyone ever heard of this ?


That would be the case if you in a high altitude area, maybe such as Colorado. But the carbs are non adjustable. The only way around this is to change the carb jetting. No matter what, the engine should run with no choke, when warmed up. If its not, something is wrong with the carburetion.


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## James (Nov 13, 2018)

russ01915 said:


> outside temperature plays a big part on choke settings. The colder it is, the more choke ( it needs to stay running). Listen to the motor and forget about the settings. If it bogs down, move the choke to where the engine runs smooth. It's more of an art than a science.
> 
> 1. first start: prime choke on start
> 2. let it run a few seconds listen to the motor. It mat start to chug a little and some blackish smoke from the exhaust, move choke to the next position.
> ...


So the temperature here in Winnipeg Manitoba Canada is -10 Celsius (14 Fahrenheit) it’s only going to get colder likely into the -20 and -30 in the next couple months. 

Would the engine need more choke or less the colder it gets?


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## Motor City (Jan 6, 2014)

James said:


> So the temperature here in Winnipeg Manitoba Canada is -10 Celsius (14 Fahrenheit) it’s only going to get colder likely into the -20 and -30 in the next couple months.
> 
> Would the engine need more choke or less the colder it gets?


No. To me its sounds like there's a problem with the carb. Yes, the cold air has a factor in running leaner, the colder it gets. But the engines are jetted for running it those cold conditions. What brand and model is the machine?


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## dr bob (Dec 12, 2015)

James said:


> So the temperature here in Winnipeg Manitoba Canada is -10 Celsius (14 Fahrenheit) it’s only going to get colder likely into the -20 and -30 in the next couple months.
> 
> Would the engine need more choke or less the colder it gets?


Colder generally needs a little longer on choke. As the engine warms up it takes less and less choke, but in colder temps that warm-up takes longer.

The carburetor's job is to mix the right amount of atomized fuel with the air passing through. When the engine is cold, that fuel stay liquid and condenses on the cold walls of the intake port on the engine. The "choke" blocks some of the air, and increases the air velocity to fool the carburetor into thinking a larger mass of air is actually flowing through. The carburetor adds more fuel to less air, so that enough actually makes it into the engine to allow it to run correctly.

Running with the choke on after warmup means excess fuel will pass into the engine, and it may misfire on every other cycle as it has to clear the excess fuel. It also blocks air so there is less total charge going in, meaning power will be down.

Follow the advice shared by others above. Reading your start protocol, I'll suggest that you open the throttle only slightly rather than all the way to "rabbit" position. Use the choke as you are, with full choke and a cold engine. Prime per the instructions after you turn the fuel on. After the engine starts, you can reduce the engine speed to idle (turtle), and let it warm up. After a minute or three of running, start gradually reducing the choke setting, and after another few minutes you'll be at idle speed and no choke. The slower engine speed means less cold air is cooling the cylinder, so it warms up a little more quickly. Go ahead and reset the throttle to allow full power, and you are ready to go.

Altitudes above 5000' may need some carburetor adjustment in the form of rejetting down slightly, but many people mistake the basic effect of the thinner air (less power) as some serious problem that might be solved with rejetting. Your local dealer has good knowledge of what's needed in your area.

More suggestions: Use fuel stabilizer in the gas can, so everything that goes into the tank is treated. When you are done using the machine, close the fuel valve and set the engine speed back to idle. Let the fuel in the carburetor run out until the engine stops on its own before storing the machine for the next use. Good time to check the oil level, clear any snow or ice that hanging on, and do a quick walk-around inspection. I typically check fuel level and top the tank at that time before putting the machine away. Let the engine cool of course before adding fuel, for fire safety. Longer-term storage and off-season prep has more steps to it. For now though, enjoy your new toy!


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## JayzAuto1 (Jul 25, 2016)

James,

There are altitude/pressure adjustments required....it is a "thing". Most small engine manufactures have a chart specifying Carburetor Jet sizing requirements for different altitudes. Not sure who should be changing the Jets, the selling dealer or the customer that got stuck buying the unit. I see many of the MTD machines with one standard size Jet on that engine, no matter where it comes from, although I'm at sea level. There are aftermarket as well as manufacture Jet kits available and that is trial and error testing. That surging you experience, is the result of not enough fuel. Older engines have the problem too, only it becomes much more noticeable as the carburetor ages and collects dirt inside. Not sure where you are located, but your dealer is being straight up with you. I've been told by some of my customers, that their "Dealers" told them to just leave the choke on until the engine sounds right..... Hmmmmmm...Great Answer.
If you want to overload your mind and have plenty of time, just look at the Honda guys on this forum and see what lengths they have gone to cure this problem.....even on new Honda's.
Personally, I just drill out the Jet myself. I use a .039 drill bit on the main Jet and I believe a #76 on the idle Jet for the 208cc engines. That seems to cure surging/stalling/low power complaints on the little MTD engines.

GLuck Jay


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## vinnycom (Nov 6, 2017)

carb is set too lean. if theres a air/fuel mixture adjustment screw turn it out, counter clockwise a half turn increments until it runs correctly at full throttle. 
fyi theres probably a limiter cap on it so maybe only minor adjustment allowed.
or dirt in carb


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