Briggs Auto Choke

[Hokiefyd]

I fixed another Briggs Quantum this weekend for a co-worker. It wouldn't start...but would cough and sputter like it was trying to. Classic symptom of a failed auto choke. Sure enough, the auto choke was stuck open. I had to remove the muffler and work it free, and used a little bit of spray lube to really free it up. I figure it'll work fine for another year, and then I'll see it again. This is on a 2010 Toro Recycler.

There has to be a better way than this. Seems the "Guaranteed To Start" warranty is for 1-3 years, and that's about as long as these silly auto chokes last before they bind up. Has anyone had better luck with these? Is there a trick or magic lubricant one can apply that will keep them working for longer than a few years at a time?

I don't like Honda's auto choke either, but at least with that one, you can bend a tab out of the way, which essentially coverts it into a manual choke (which I have done on my own GCV160). The Briggs requires partial disassembly (and additional parts, if there's a way to convert this into a manual choke.

 

[AlienBug]

The autochoke on my Honda GCV160 has worked perfectly for eight years. Before that my Briggs-powered mower ran perfectly for six years before I gave it away. It is still running with a perfectly-functional autochoke.

 

[Quest]

With a handful of Walbro LMS manual choke carbs and some air-fitler box plates (w/ primer bulb), I typically retrofit these pesky auto-choke type engines with the primer bulb settings type.

Works very nicely afterwards.

Q.

 

[440Magnum]

Originally Posted By: Hokiefyd
I fixed another Briggs Quantum this weekend for a co-worker. It wouldn't start...but would cough and sputter like it was trying to. Classic symptom of a failed auto choke. Sure enough, the auto choke was stuck open. I had to remove the muffler and work it free, and used a little bit of spray lube to really free it up. I figure it'll work fine for another year, and then I'll see it again. This is on a 2010 Toro Recycler.

There has to be a better way than this. Seems the "Guaranteed To Start" warranty is for 1-3 years, and that's about as long as these silly auto chokes last before they bind up. Has anyone had better luck with these? Is there a trick or magic lubricant one can apply that will keep them working for longer than a few years at a time?



I don't know if you can even get it anymore, but the old Mopar "heat riser lubricant" designed for the notoriously sticky exhaust manifold diverters on Chrysler engines from the 60s-80s is great for this job. GM used to have an equivalent ("high teperature choke lube" or something like that). My last can of the Mopar stuff has lasted me 10+ years since I finally just disabled the heat risers on all my vintage engines.



Well, I couldn't turn up an equivalent for the old Mopar spray, but I think this is the GM product in tube form. Not as easy to apply, but once there it should (if its as good as it used to be) last a long time:



Linky here.


FWIW, I haven't had a lick of trouble with my Recycler auto-choke Briggs and its older than that one... but I'm pretty meticulous about keeping it clean. I rinse it down every few uses, then start it up and let it run until thoroughly dry before putting it away, or else blow it down with compressed air if I can't take the time to let it dry. There's not much I hate more than opening up an air-cooled engine and finding the cooling fins choked with grass and debris. I think the resulting overheat is pretty rough on those auto chokes, too.

 

[stephen9666]

My MTD-made Craftsman mower has a Briggs with autochoke and I've been wondering if it will ever fail. At this point it's about 7 years old and still working great.

 

[92saturnsl2]

Yeah, I'm not quite sure I see the purpose of the auto-choke. It's not like the manual version was some sort of rocket science.

I've seen more than my fair share of Briggs engines equipped with it fail to start, and need repairs.

My three year old GCV160's auto-choke is starting to bind up, such that when you enable it, it does not auto-release, essentially functioning like a manual choke. It's right on the side of the engine cover, where it's easy to bang into the air conditioning unit and other obstacles.

 

[Falken]

Had an Auto Choke on a WM Brute with a B&S engine.

Never a problem, but then again I always stored the lawn mower in a garage and not in the rain or a damp leaky shed.

 

[Hokiefyd]

This one still looked like new (the engine's really only 3 seasons old). It felt like it had no lubricant at all, and the sheetmetal "cup" at the base of the lever was dragging against the little thermostat housing below it. I don't know if these are supposed to be lubricated from the factory, but I'm sure that the heat from the muffler flashes any lubricant off after so many hours.

It's an interesting idea, and I like the idea conceptually. But the implementation could have been done better in my opinion. The little thermostat mechanism appears very cheap and adjustments are only allowed in gross increments, by physically bending levers. It's just not a very elegant design to me.

If it could have been designed such that the user could intervene without disassembling the to of the engine, it at least would allow them to continue to use it until they could have it serviced.

As an aside, I think if people knew how easy it was to replace this thing, fewer people would have to bring the mower to a shop (or to someone like me) to fix it. They just know "it doesn't start" and it could be anything...

 

[gizzsdad]

Originally Posted By: 92saturnsl2
Yeah, I'm not quite sure I see the purpose of the auto-choke.


I'm not sure - but I was under the impression that auto-chokes are now mandated by the EPA or some other bureaucracy. I'm perfectly OK with being educated on this.

 

[Hokiefyd]

Originally Posted By: gizzsdad
Originally Posted By: 92saturnsl2
Yeah, I'm not quite sure I see the purpose of the auto-choke.


I'm not sure - but I was under the impression that auto-chokes are now mandated by the EPA or some other bureaucracy. I'm perfectly OK with being educated on this.


I'm not sure if the choke mechanism itself is being mandated, but they may be in response to certain performance standards being required. Kind of like how 20 grade oils aren't required by the EPA, but are often used, among other things, to achieve the performance (economy) required.

I understand that a choke uses less fuel than a primer, which is why we generally don't see primers on these engines anymore. But a manual choke has the potential to be left on longer than required, using more fuel than a choke that automatically pulls itself off, which is why we generally don't see manual chokes on these engines anymore. There are likely performance standards that can be met by using these types of devices rather than by re-engineering the engines themselves (to run cleaner) or by adding treatment devices (like catalytic converters).

The two forms of auto choke that I've seen are from Briggs & Stratton, which thermal-based (thermostat element next to the muffler), and from Honda, which is time-based. Honda's system (at least the older ones, where you set it and then it pulls itself off) uses a spring-loaded lever which is released when you pull down on the operator presence bail. But it runs against a friction surface to control the rate at which the lever returns. Pull the bail (and the choke lever begins to slowly return to off) and rip the cord. The engine will start, and in a few seconds, the choke will pull itself off.

With Honda's system, you can intervene in a number of ways. You can reach down and hold the choke lever on a little longer if it needs to stay on longer (like on a cold day), or you can push it forward faster on a hot day to remove the choke sooner. Or you can bend or remove the little tang that releases the lever, which turns it into a completely manual choke.

I see the merits of both systems, and understand the likely justification for them. At least both are easy to fix if you know the symptoms.

 

[yeehaw1960]

Usually just have to remove the plastic top cover and move the lever back and forth a few times to loosen things up.

Did have a lady who ran her brand new Toro out of gas and, because it was warm, the choke stayed open and wouldn't help the new gas get from the tank to the carb bowl. She let it cool down and the choke closed and syphoned the gas through the hose and into the bowl when she pulled on the rope again.

And did you know, that mower started right up. Momma always said, mowers are like a box of chocolates; you never know what you're gonna get. Except that most of the parts will come from China. And that's all I have to say on that particular subject.