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Push mower wont stay running unless I hold air vane open for 45sec

#1

M

moebattler

Mower model - Troy-Bilt 12AV566N011
Briggs Stratton model - 126T02-0487-B1
Auto Choke

Problem:
Mower sputters after start and eventually shuts off. Found if i manually hold the air vane arm open for 45sec to 1min...everything warms up and the mower runs fine. I have to do this for every cold start.

What i did:
Replaced gasoline
Changed oil
Replaced spark plug
Cleaned carb
Replaced spring which controls air vane
Replaced thermostat (which pushes against the air vane to open)
Did not replace air vane itself because its just a piece of plastic and seems like in fine shape.

So the mower works fine after what I mentioned but quite a pain to hold that open after every start.

Any suggestions are appreciated
Thanks


#2

R

Rivets

Did you adjust the air vane when you replaced the thermostat? Sounds to me like the choke is not opening properly on startup. Should have been instructions on how to adjust with the new thermostat.


#3

M

moebattler

Thanks for the response. Yes I placed it so the thermostat hits and pushes against the middle part of the vane. When i manually move the thermostat, it moves easily and pushes the vane without any resistance. Seems like its where it should be.


#4

M

moebattler

Can I take the muffler off and try to watch what the thermostat does while starting?


#5

V

VegetiveSteam

Just a couple of thoughts. Maybe see if you can find out what the RPMs should be on this engine and make sure they're not below what they should be. If the RPMs are low there might not be enough air movement to force the air vane to move as far as it's supposed to. I don't know if this is even possible to get out of adjustment but I'd also check that the bracket that the air vane spring attaches to didn't somehow get bent and putting excessive tension on the spring in turn not letting the air vane move as far as it should.


#6

V

VegetiveSteam

moebattler said:
Can I take the muffler off and try to watch what the thermostat does while starting?
Click to expand...
Without the muffler I'm not sure the thermostat will work correctly so that may not tell you anything.


#7

M

moebattler

Thanks Vegetive Steam ..appreciate the response - I like the idea of checking brackets where spring is attached but thinking I don't want to adjust too much because all works fine after the engine 'warms up' and do not want to cause an additional problem. And you're right ..can't have the muffler off to monitor the thermostat

​



#8

E

enigma-2

After reading all of the posts, seems to always come back to the thermostat not opening or opening far enough.


#9

V

VegetiveSteam

moebattler said:
Thanks Vegetive Steam ..appreciate the response - I like the idea of checking brackets where spring is attached but thinking I don't want to adjust too much because all works fine after the engine 'warms up' and do not want to cause an additional problem. And you're right ..can't have the muffler off to monitor the thermostat

​

Click to expand...
I agree. You don’t need to cause more problems. Just see if anything looks out of place or bent. It’s a pretty simple system so there aren’t too many things to check.


#10

B

bertsmobile1

The important question
Are you holding the choke on or off
The air vane pulls against a spring when the engine is cold
So the choke is only on for a second or two
Once the engine gets to 1/2 speed the air vane should hold the choke OFF
When hot the thermostat holds the choke OFF because you do not need the choke to start a hot engine
To me it sounds like the spring is too weak to hold the choke on long enough for the engine to warm up
The thermostat must be working fine if the mower hot starts OK


#11

M

moebattler

Great response thank you - I guess I am holding the choke OFF to keep it from shutting off. I replaced the air vane spring and that seems tight. But I did not replace the choke return spring ..maybe that is my next thing to try. Thanks again

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#12

Tiger Small Engine

Tiger Small Engine

moebattler said:
Great response thank you - I guess I am holding the choke OFF to keep it from shutting off. I replaced the air vane spring and that seems tight. But I did not replace the choke return spring ..maybe that is my next thing to try. Thanks again
Click to expand...
These air vane chokes are very touchy and the correct spring tension is the key. Spring could have been replaced (incorrectly), or have wrong tension and causing problem.


#13

M

moebattler

Is there a difference between the
690354 CHOKE RETURN SPRING
699056 GOVERNOR SPRING

I see where the Governor Spring goes but cannot find where Choke Return Spring is installed?


#14

V

VegetiveSteam

moebattler said:
Is there a difference between the
690354 CHOKE RETURN SPRING
699056 GOVERNOR SPRING

I see where the Governor Spring goes but cannot find where Choke Return Spring is installed?
Click to expand...
Yes they are different springs. The choke return spring stretches across the top of the carb from the choke shaft to a bracket that is actually part of the carb.


#15

M

moebattler

Thanks - see pic. Air vane spring and Governor spring shown. You are saying the Choke Return Spring is underneath the metal plate?

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#16

V

VegetiveSteam

moebattler said:
Thanks - see pic. Air vane spring and Governor spring shown. You are saying the Choke Return Spring is underneath the metal plate?
Click to expand...
No but I may have to plead ignorant on this one. Yours is different than the ones I've seen. I don't think yours uses a choke return spring. Like you, I don't see where it could go and with what the air vane spring looks to do I don't see the need for a choke return spring. The ones I have seen have the spring and the mounting points for the spring all incorporated as part of the carb itself. Yours is a different set up so I may have to yield to someone more familiar.


#17

R

Rivets

To me it looks like both springs are hooked up correctly, but the choke return spring looks a little taut.


#18

B

bnicol456

Rivets said:
Did you adjust the air vane when you replaced the thermostat? Sounds to me like the choke is not opening properly on startup. Should have been instructions on how to adjust with the new thermostat.
Click to expand...
Yes, sounds like a choke. If it was working before, you may want to spray with WD40 or something like that first to see it it is just stuck. I would try that first before adjusting.


#19

S

Smokindog

moebattler said:
Mower model - Troy-Bilt 12AV566N011
Briggs Stratton model - 126T02-0487-B1
Auto Choke

Problem:
Mower sputters after start and eventually shuts off. Found if i manually hold the air vane arm open for 45sec to 1min...everything warms up and the mower runs fine. I have to do this for every cold start.

What i did:
Replaced gasoline
Changed oil
Replaced spark plug
Cleaned carb
Replaced spring which controls air vane
Replaced thermostat (which pushes against the air vane to open)
Did not replace air vane itself because its just a piece of plastic and seems like in fine shape.

So the mower works fine after what I mentioned but quite a pain to hold that open after every start.

Any suggestions are appreciated
Thanks
Click to expand...
R U burning "corn liquor"? Find a non-ethanol station near you and use zero corn. Also, buy a bottle of your favorite gas stabilizer and add it to your gas can before each fillup at the 2 year rate. Your problems will likely go away over time in ALL your small engines. MY rule of thumb, if it's less than 25HP this is what I do.

Also, when you replaced the carb, make sure you got the spring for the governor back in the right hole. I've made that mistake before with similar results.


#20

T

Tom O'

moebattler said:
Mower model - Troy-Bilt 12AV566N011
Briggs Stratton model - 126T02-0487-B1
Auto Choke

Problem:
Mower sputters after start and eventually shuts off. Found if i manually hold the air vane arm open for 45sec to 1min...everything warms up and the mower runs fine. I have to do this for every cold start.

What i did:
Replaced gasoline
Changed oil
Replaced spark plug
Cleaned carb
Replaced spring which controls air vane
Replaced thermostat (which pushes against the air vane to open)
Did not replace air vane itself because its just a piece of plastic and seems like in fine shape.

So the mower works fine after what I mentioned but quite a pain to hold that open after every start.

Any suggestions are appreciated
Thanks
Click to expand...
Carburetor fuel/air mixture needs adjusting - my first opnion. Idle may need adjustment during/afterwards as the fuel/air is altered.


#21

M

moebattler

THere are no levers or screws on my carb to adjust fuel/air


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