How Does The Auto Choke Work on a Briggs & Stratton? No Start Problem..

In this video I'll cover the auto choke thermostat and how it works. Also what to look for in the event of a failure and a demonstration with heat of the thermostat in action. I also cover a possible fix for it.

[@mowwow1998]

excellent straight to the point video, especially liked the demo with the torch showing exactly how the thermostat works..

[@JLPicard440]

TYSM! So glad I could help...

[@blackstonecap]

Thanks for the great video and clear explanation. As a non-mechanic, I've been monkeying with my machine for a week or two trying to gigure out why it's only starting with ether and running for a couple seconds. You got a new subscriber.

[@JLPicard440]

TYSM for the sub! I am so glad I was able to help you... 😊

[@stevesnider6817]

Good instructions. I especially appreciate the visual aid demo.

[@JLPicard440]

Glad it was helpful!

[@jasonagcaoili3246]

Thank you for this video! It helped me diagnose what was going on after I replaced the carb and couldn't start it when it was cold. Now I know how the auto choke works on a mower!

[@JLPicard440]

You're welcome! So glad I was able to help...

[@thomaslanik7215]

Very enlightening! Thank you from Knoxville Tennessee.

[@JLPicard440]

Excellent! You're welcome and thank you for the great feedback..

[@eddiesheeran5791]

Great video! I'm working on a Masport with a Briggs engine, and the choke is staying on even when the engine is hot. When you try to start it hot, it takes 10 pulls & blows black smoke for a second when it finally starts up.

[@JLPicard440]

Oh wow... there may be something wrong with the thermister that goes on the muffler maybe? Have you looked at that?

[@eddiesheeran5791]

@@JLPicard440 So far all I did was blast the little thermostat with a torch like you did, and move it back & forth with my finger to free it up. I was doing some testing yesterday & it might be fixed already! I always do multiple tests to ensure there are no more intermittent problems, but the auto choke was actually staying unchoked when the engine was hot, so your video is right on the money! This mower was covered in clippings & sitting in my neighbor's garage for who knows how long, so the little auto-choke probably seized up because the manufacturers didn't seal it from moisture & corrosion! ¯\_(ツ)_/¯

[@JLPicard440]

Oh cool! Yea i've worked those thermostats loose before and they started working... Hopefully that's all it was.. 😀

[@inquisitvem6723]

My choke lever on my Husqvarna 3200 psi is stuck in the middle. It won’t go back to the cold position(way left). I’m unable to start it after using it for several hours the other day. Before it died it started for 30 seconds and then sputtered wit smell of oil burning or something. It still had half oil left and plenty of gas. This is a brand new pressure washer too.

[@JLPicard440]

HI... If it's brand new can you take it back? If not, you still should be able to get a warranty repair... I think the thermostat might be bad, but why should you fix it if you can get them to fix it under warranty...

[@inquisitvem6723]

@@JLPicard440 can’t take it back because I waited for over two years to use it. It was sitting new in my garage for two years. Are you saying even after a little two years, it’s still under warranty?

[@JLPicard440]

HI, no I hadn't realized it sat for that long. I doubt if it's under warranty... You can check to see what the warranty period is. For example Toro is 2-3 years depending on the application.

[@davep4703]

I have a B&S 450 OHV mower. Is it's possible to change out the prime to start carburetter for the auto choke together with the heat activated unit.

[@JLPicard440]

HI, I believe it should be ok. If I remember right the choke thermostat is part of the muffler and doesn't bolt to the block. I don't see why it wouldn't work.

[@WastelandProject]

😦😦Surgical diagnosis. Thank's👍👍👋👋👌👌

[@JLPicard440]

HI! Thanks for the great feedback... 😊

[@yenbbc8840]

mine starts up but doesn't fully open the butterfly. blows black smoke and shuts down. should i bend the wire or replace the thermostat? if i hold the butterfly open it runs as it should.

[@JLPicard440]

Good question.... IF you take a look at the linkage between the muffler and the carb does it look bent? If it looks normal your thermostat is probably bad...

[@yenbbc8840]

@@JLPicard440 thanks for your reply. i bent the bracket that the thermostat is mounted on towards the carb and the problem was solved. if it acts up again i will replace the thermostat. the mower is new and only has 1 season on it. your video inspired me to give this problem 1 more look. thanks again for your help.

[@JLPicard440]

That's awesome! I love a free fix... 😊

[@Tterryups]

A thermisister is an electronic part, we are working with a thermostat on the choke

[@JLPicard440]

I worked on electronics for many years, so must have been a slip ... 😊

[@Nova-m8d]

Great video but they've dumbed down the choke with over-engineering to the point it makes me want to throw this new lawnmower in the trash. Man, I miss my old lawnmower with the manual choke so much. I only bought this mower because that's all the store had above 6 hp.

[@JLPicard440]

Ive actually found that auto-choke mechanism to be pretty reliable. It can fail, but usually doesn't. Yes of course the old manual choke with the cable was more reliable... 😊

[@WilliamHollinger2019]

Dang i want to remove my.

[@JLPicard440]

Thank you 😊

[@A-r-o-h]

Another reason to only buy their primer start engines 😂

[@JLPicard440]

I've actually found the auto choke to be pretty reliable. The primer ball engines often had a problem with the air box leaking air between the box and the carburetor and the primer ball didn't work well when that happens... 😀

[@A-r-o-h]

@@JLPicard440 Hmm, I guess they both have their problems. However, I usually hear far more complaints about the autochokes than the primer. To each his own.

[@A-r-o-h]

Just wondering, what year of engines experienced these primer problems? Are these the old flatheads or the current models made in the last 5 years or so?

[@JLPicard440]

Definitely not the older flat heads! I haven't seen one of those in many years. I did a google search to see if I could figure out when they stopped making the primer bulb, but couldn't find anything on that. Seems like it's been close to 10 years. Any of those ones through the 2000s had a problem with the air box. Sometimes you can double or even triple the gasket and that'll take care of it, but the air box will warp causing this problem.

[@A-r-o-h]

@@JLPicard440 Good to know! I guess those warped from heat radiating off the metal carb combined with cheap plastics. I'd think most thermoplastics have gotten cheaper and more advanced with time. Will have to see with these new plastic resin carbs.

[@LunaDaSavage]

Youdaman

[@JLPicard440]

TYSM!

[@David-oh3rh]

Stupid nonsense by Briggs. A choke cable would literately last forever for homeowners that mow 25-35 times per year and works perfectly with little to no maintenance. This "auto" choke is ridiculous and will STUPIDLY will close the choke valve on an engine that is still at operating temp if you stop and take a 10 min break after mowing for awhile.

[@JLPicard440]

I agree... A cable is timeless (unless you leave it outside!)... This system mostly works, but the 10 minute break scenario could be problematic... 😊

[@David-oh3rh]

@@JLPicard440 It is..and maybe dependent on outside temps. But...I've had mine not start after mowing for 30-45 minutes and have to unscrew the air filter cover,insert a screwdriver to push the butterfly valve open and it starts right up--coughing somewhat from the excess fuel in there. It's ridiculous!!

[@JLPicard440]

Yea that is a pain. I haven't had much trouble like that, but probably just haven't hit the right combination of events yet!... 😂