Briggs and Stratton Auto Choke on Toro Problem

[Stihleer]

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

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?

 

[StarTech]

IT does sounds like a faulty thermostat. The replacement PN is 798938 . or the carburetor could be missing the choke spring. Here is image of the carburetor showing the spring. The problem is that Briggs don't sell the choke seperately from the carburetor.

 

[Rivets]

The choke return spring is part number 798900.

 

[StarTech]

Ahhh after downloading the IPL from Briggs I found the choke listed but it is list as 799179 and not as Rivets listed as 798900. My fault for trusting outside vendors instead just downloading the IPL from Briggs in the first place.

They do appear to be two different springs.

 

[Stihleer]

It looks like all springs and linkage are there. Here is a video of the choke lever going crazy I have to hold it with my fingers to keep it from moving but as soon as let go it goes crazy again.

Watch nar4by | Streamable

Watch this video on Streamable.

streamable.com

 

[Stihleer]

could the linkage be causing this issue? The governor spring post was bent inwards pretty bad and was down on RPM. Looks like someone hit a low branch with it. The linkage is right next to the governor spring. Makes me think.

 

[Rivets]

Star is correct, I used the wrong engine type number.

 

[StarTech]

I never seen an engine doing that to the choke. It as something bouncing the throttle linkage but it is not moving that I can see. Now I am curious as to the cause too. Hope you find the cause and let us know what it is.

 

[bertsmobile1]

I had that problem a few weeks back.
I ended up buying a new carb but for curosity I swapped the spring from the new to the old and that stopped the choke flapping .
The linkage from the auto choke had also been bent a bit from running into things so I bent it back to tighten the Off position and that cut down the amount of flapping a lot but it did not stop till the springs were swapped.
This is the one that was running rich

 

[Rivets]

If the choke is bouncing while the engine is running, you need to tighten the spring tension by moving the tab the spring is hooked to, in toward the engine. This spring is designed to close the choke when the end is closed.