Briggs and Stratton Auto Choke on Toro Problem

[Kevinmcc2]

Hello, I have a problem with a Toro Timemaster Model #: 20199 with a briggs 190cc #121S020130F1 engine.

This only happens after I engage the blades and on a cold mower.

The mower when it is cold runs horrible. I noticed that the auto choke linkage and arm on the carb flaps and flutters back and forth very fast and violently. This linkage goes to a thermostat on that muffler to the carb. If I hold the linkage in the choke OFF position the mower runs great and has good power but when i dont hold it the choke flap opens and closed at a very fast rate like its flapping in the wind.

Could this be a faulty thermostat, linkage, carb?

https://streamable.com/nar4by

https://streamable.com/6od3rb

It seems like when I engage the blades the one plastic piece rotates and thats when the choke starts to flap. the second video shows it a lot better.

I have tried a new choke return spring, and also cutting it to shorten it to apply more spring tension to help it hold the choke butterfly but nothing. Also, I have checked the govenor by removing the crank case cover and still all there.THis o

 

[mk378]

The thermostat is a bimetal coil-- either cold or hot it should apply some definite force on the arm and push rod. If it flaps back and forth it is broken inside.

 

[Kevinmcc2]

Originally Posted by mk378
The thermostat is a bimetal coil-- either cold or hot it should apply some definite force on the arm and push rod. If it flaps back and forth it is broken inside.



There is some force on that thermostat and it pushes open when fully warmed up. When cold tho it seems the plastic linkage doesnt touch the choke linkage at all until it is hot? Do you think the spring inside the thermo is weaked to a point it should be touching the choke linkage at all times?


I just reread your post and It answered my question, gonna order a new thermostat,

 

[Kevinmcc2]

After looking at the linkage again how can the thermostat push the choke linkage? Maybe the linkage is missing something or not correct?

 

[Kevinmcc2]

https://streamable.com/7is216

 

[MasterSolenoid]

Could you be missing a Spring on the part that's vibrating ?
I would guess it would be a very small Coil Spring.
Look for a Hole or Tab that a spring could hook on to.

Then look in a Manual showing your Carb and any Springs.

My Toro with Auto Choke was giving me problems starting. Took 12 pulls.
Because of rigorous cleaning, I knocked the small spring off.
Once the spring was replaced, it starts on the second pull.

 

[Kevinmcc2]

Originally Posted by MasterSolenoid
Could you be missing a Spring on the part that's vibrating ?
I would guess it would be a very small Coil Spring.
Look for a Hole or Tab that a spring could hook on to.

Then look in a Manual showing your Carb and any Springs.

My Toro with Auto Choke was giving me problems starting. Took 12 pulls.
Because of rigorous cleaning, I knocked the small spring off.
Once the spring was replaced, it starts on the second pull.



I replaced the spring on the choke that is vibrating, was the firs thing I did since it was cheap and and figured that would be the problem. Sadly it didnt. I have had this problem over a month now and its a big mystery lol. Should I just bite the bullet and throw a thermostat on it? Its around 25 bucks.

 

[Quest]

I own a couple of auto-choked B&S mowers, and none of them levers should be flapping/vibrating back and forth when cold (shortly after cold starts).

If you experience that and granted that the carb is not an issue, then you may have to consider replacing the choke mechanism.

Q-TD

 

[sweezy722]

I am probably the only one to think this way but I would try to put a manual choke on it. Cheap and reliable.

 

[andyd]

Only if it came with one, Sweezy

 

[Kevinmcc2]

So just ordered a cheap $14 carb from amazon and put it on just now. Fired right up and choke works perfectly...

Tried to examine and compare the two to see if the oem had a missing or broken linkage or anything but looked exactly the same.

Maybe something internally broke on the oem carb? So strange.

Now I'm gonna debate buying a new Briggs oem carb for 45 or just rock the cheapo!