Briggs auto choke..

[scoyote]

This is a common problem with people shutting down to dump clippings and then trying to restart a hot engine. The mower defaults to choke when it shuts down ready for the next cold start--it has a tiny spring to assist a return to choke--Once the engine starts the unobstructed air vane and a correctly operating thermostat should overwhelm the tiny spring and hold the choke open---The problem is the restart of a hot engine if the choke stays on with a faulty auto choke thermostat not doing its job .Whateveer happened to pull your choke on and push it off---too easy! Best to not shut down imho

 

[TobyU]

Ok.. no one has explained it like that to me.. no one has said that the flywheel air pushes the wind vain to the open piosition..
Thank you..
186T02-2299-B1
It’s also a toro 20331
Cowboy..

I assumed from your earlier comment where you were wondering if someone sold you the wrong tension spring, that you understood basically how the system worked.
You could be on to something with the spring as it is a very small spring and very weak.
As soon as you start the engine, it needs to quickly blow the air vane away from the flywheel so the choke will open and it needs to do this before the engine even gets up to full speed. I would say that somewhere around 3/8 to 1/2 engine RPMs it should already be blowing it open.
That gives you an idea how little tension is being exerted to keep it in its normal position when the engine is off and cold.
I also lube the lever at the bottom near the muffler and move it back and forth a few times to make sure it can move easily as the engine warms up to keep the choke open.
The comments about hot restart problems are fairly common but normally only after you let the lawn mower sit for over 8 or 9 minutes and especially when it's in the shade and when there's a breeze. They don't intend for you to leave a lot more off that long on a hot restart.
It's not a computer controlled ECM but just old school manual heat risers and stuff so they can't make it adapt for all situations.
They expect you to go out to your mower after sitting all week long and put gas in it and check the oil.
It will be cold so they have the choke by default in the closed position.
As soon as you pull the rope and it starts to spin up to speed, it blows the air vane open which overcomes the spring tension and opens the choke.
Within just a couple of minutes the engine is hot enough so the heat riser choke disengagement lever thing over by the muffler rotates towards the front of the engine and holds the choke open so when you turn the engine off the choke will still be open because it will be hot and not need to choke for the restart.
They assume you're going to mow your entire lawn or if you have to turn it off to refuel that only takes under 2 minutes so it will be fine on the hot restart and if you're going to empty your bag that again only takes about a minute or so so no problems because the muffler choke pull off doesn't start to close until it cools off more than that.
But if you wait too long like 7 8 9 10 minutes something like that especially if there's a breeze because that muffler is thin sheet metal, it will cool off enough that it will start to work its way back towards the back of the engine and close and now if you don't pull the rope really really hard and it doesn't start in the first two pulls, it will be flooded and it won't start for about 45 minutes.

There is an adjustment on this and I don't understand why they don't come from the factory better adjusted. When you remove the shroud you can see a little lines on the end that show you the adjustment notches and they are almost always not opened up and there's a lot of play before it hits the plastic part of the air vane.
I have found that if you open them up where they are almost touching the plastic air vane, you will have better hot restarts.

 

[Tiger Small Engine]

I assumed from your earlier comment where you were wondering if someone sold you the wrong tension spring, that you understood basically how the system worked.
You could be on to something with the spring as it is a very small spring and very weak.
As soon as you start the engine, it needs to quickly blow the air vane away from the flywheel so the choke will open and it needs to do this before the engine even gets up to full speed. I would say that somewhere around 3/8 to 1/2 engine RPMs it should already be blowing it open.
That gives you an idea how little tension is being exerted to keep it in its normal position when the engine is off and cold.
I also lube the lever at the bottom near the muffler and move it back and forth a few times to make sure it can move easily as the engine warms up to keep the choke open.
The comments about hot restart problems are fairly common but normally only after you let the lawn mower sit for over 8 or 9 minutes and especially when it's in the shade and when there's a breeze. They don't intend for you to leave a lot more off that long on a hot restart.
It's not a computer controlled ECM but just old school manual heat risers and stuff so they can't make it adapt for all situations.
They expect you to go out to your mower after sitting all week long and put gas in it and check the oil.
It will be cold so they have the choke by default in the closed position.
As soon as you pull the rope and it starts to spin up to speed, it blows the air vane open which overcomes the spring tension and opens the choke.
Within just a couple of minutes the engine is hot enough so the heat riser choke disengagement lever thing over by the muffler rotates towards the front of the engine and holds the choke open so when you turn the engine off the choke will still be open because it will be hot and not need to choke for the restart.
They assume you're going to mow your entire lawn or if you have to turn it off to refuel that only takes under 2 minutes so it will be fine on the hot restart and if you're going to empty your bag that again only takes about a minute or so so no problems because the muffler choke pull off doesn't start to close until it cools off more than that.
But if you wait too long like 7 8 9 10 minutes something like that especially if there's a breeze because that muffler is thin sheet metal, it will cool off enough that it will start to work its way back towards the back of the engine and close and now if you don't pull the rope really really hard and it doesn't start in the first two pulls, it will be flooded and it won't start for about 45 minutes.

There is an adjustment on this and I don't understand why they don't come from the factory better adjusted. When you remove the shroud you can see a little lines on the end that show you the adjustment notches and they are almost always not opened up and there's a lot of play before it hits the plastic part of the air vane.
I have found that if you open them up where they are almost touching the plastic air vane, you will have better hot restarts.

These auto chokes are a pain and a nuisance sometimes. Some take longer than others to open completely.

 

[TobyU]

These auto chokes are a pain and a nuisance sometimes. Some take longer than others to open completely.

True but if you adjust the end so it doesn't have so much slack before it actually starts to open the choke and if you lubricate the bottom near the spring area and make sure it's not rubbing against on either side as it moves, they become quite consistent with their opening and closing.

 

[VRR.DYNDNS>BIZ]

Yes it’s moving freely.. I wonder if someone sold me the wrong strength air Cain spring.. but I tried stretching other springs and such for different tensions..
Also the thermostat doesn’t even start to hold it open until it’s pretty much completely warmed up.:
Cowboy..

tHE SPRING IS A TINY THING AND THE PARTS BREAKDOWN IS CONFUSING AND THE WRONG SPRING IS OFTEN SUPPLIED OR REFERENCED. The air flow pushes the vane and also the choke off as rpm rises. If a manual throttle, and it obtains full rpm but choke is not off, the thermostat has no impact under this air movement. Some have envisioned the vane to be hooked together with the thermostat. That is incorrect, the thermostat pushes the vane open to it's minimal choke level at lower rpm's, yet at higher rpm's the vane should move forward by simple air flow. watching the pivot end where the vane is supported on the carb gives observation of vane movement. And yes, some vanes have a bit higher boss that the shoulder bolt keeps free, thus a bit of binding can be found. My bet is the spring.

 

[ThatOneGuy1968]

tHE SPRING IS A TINY THING AND THE PARTS BREAKDOWN IS CONFUSING AND THE WRONG SPRING IS OFTEN SUPPLIED OR REFERENCED. The air flow pushes the vane and also the choke off as rpm rises. If a manual throttle, and it obtains full rpm but choke is not off, the thermostat has no impact under this air movement. Some have envisioned the vane to be hooked together with the thermostat. That is incorrect, the thermostat pushes the vane open to it's minimal choke level at lower rpm's, yet at higher rpm's the vane should move forward by simple air flow. watching the pivot end where the vane is supported on the carb gives observation of vane movement. And yes, some vanes have a bit higher boss that the shoulder bolt keeps free, thus a bit of binding can be found. My bet is the spring.

I put a new air vane on it and used the spring I bought from Amazon.. the old vane had a small piece broken off of it somehow.. the new vane was all over the flywheel cover, I had to heat it and teeekvit a little which causedvitvtovgetcstuckvonvthe coil, so I did a little trimming and final got it moving nicely and not touching anything.. I still have the same problem tho and I’m going after that spring next:: I have a hood friend that his Husqvarna lawn tractor was dead and he talked me into repairing it.. I bring thisvup because it also has an automatic choke and the spring is very weak.. like I’d guess three or four times weaker than the spring in that farn toro, so I’m going after that spring now.
Thank you all for your experience and knowledge.. it means a lot to an old cowboy that is tryna figure it out on a budget..
Cowboy..