Tell me about small engine (snowblower) chokes

[seepy83]

Can someone explain what a Choke on an engine is for, or why mine might not be working as expected?

I got a new snow blower earlier this year (Ariens Compact 22), and according to the manual, I'm supposed to turn the choke on when I start it, let it warm up, and then turn the choke off. Well, it doesn't start when the choke is on, but fires right up when I have the choke off.

 

[jaha2000]

This new, or new to you?
Idea is the fatten the mix to make it start easier when cold.
I have an ariens as well. Choke on, couple pumps of the primer bulb, starts right up. Runs for 30 seconds, flip the choke off and away we go.

 

[seepy83]

This new, or new to you?

Brand new.

 

[LTC8K6]

The choke blocks off most of the air, making the fuel mixture richer, for running well when cold. Once the engine has warmed up a little, the richer mixture is no longer needed, and the choke can be opened to allow full air flow into the engine, returning the mixture to normal.

 

[SpatiallyAware]

What's the ambient temp?


If it's not freezing cold then it may not be necessary to use the choke.

 

[seepy83]

What's the ambient temp?


If it's not freezing cold then it may not be necessary to use the choke.

Pretty damn cold...In the 10-25 deg F range the few times I've used it, maybe even under 10 F one of the times.. It runs very well, and starts up with 1 pull, but only when the choke is off.

 

[DaTT]

Pretty damn cold...In the 10-25 deg F range the few times I've used it, maybe even under 10 F one of the times.. It runs very well, and starts up with 1 pull, but only when the choke is off.

I hate to sound like an ass, but is it possible that you are getting "on" and "off" mixed up?

Next time you fire it up and it gets to operating temperature, turn the choke "on" and see if it bogs down. If it does, then the choke is working fine.

It is called "choke" because it "chokes" the air out and lets very little air in.....as stated in above responses.

Mine won't cold start without the choke...let it run for about 20-30 seconds then turn the choke off....longer if it's extremely cold outside.

 

[Zenmervolt]

A "choke" is a method of providing cold start enrichment with a carburetor.

There are two methods of achieving this. First is the traditional "choke" which involves cutting off much of the air supply, but doing so upstream of the carburetor's venturi. The result is that the incoming fuel/air mixture has a higher amount of atomized fuel in it. (This is all due to some complex physics that doesn't need to be delved into too deeply right now.) The second method is technically an "enricher" but is generally still referred to as a "choke" as well. This method uses an additional jet in the carburetor that is only open when the enricher ("choke") is on. Because there's another jet from which fuel can be pulled, the mixture is richer than normal.

If the carburetor is adjusted absolutely perfectly, it's quite possible that no choke is needed even when the engine is completely cold (i.e. has been off for several hours) on cool days. However, on very cold days (i.e. temperatures below freezing) most engines will need the choke for cold starts.

Remember that a "cold start" generally means the engine has not been run for at least a couple of hours. If you're using the choke when trying to start a warm engine, you'll just flood it and make it harder to start.

ZV

 

[seepy83]

I hate to sound like an ass, but is it possible that you are getting "on" and "off" mixed up?

Next time you fire it up and it gets to operating temperature, turn the choke "on" and see if it bogs down. If it does, then the choke is working fine.

It's blatantly obvious which way the choke is on (shown as the "starting position"), and which way is off ("running position"). If I turn it on after running the engine for a while, the engine stalls out.

 

[denis280]

This is good.i would worried if you would have to run it with the choke on or half way

 

[DaTT]

It's blatantly obvious which way the choke is on (shown as the "starting position"), and which way is off ("running position"). If I turn it on after running the engine for a while, the engine stalls out.

Then it sounds like the choke is working fine.

Try giving it one more prime before starting, mine says 3 primes but I give it 4. However, if you're not having any trouble getting it started without the choke, I wouldn't worry too much about it.

 

[njmodi]

+1 on the comments that it's working fine. I have a over 10-yr old Ariens ST724 that I recently acquired and rebuilt carb/tuned. It barely ran with choke closed when I first got it and constantly stalled under load.

After my rebuild/clean of the jets, it runs like a champ and I don't even have to close the choke to start it - like your brand new unit, it quickly stalls if I close the choke (too rich a mixture).

Don't worry and enjoy your new machine. :thumbsup:

 

[LTC8K6]

It's blatantly obvious which way the choke is on (shown as the "starting position"), and which way is off ("running position"). If I turn it on after running the engine for a while, the engine stalls out.

That is proof that the choke is working.

If it starts without the choke, that's probably okay. The choke isn't always necessary.

The only thing I can think of, is that the carb is adjusted too rich, and it's burning more fuel than it should all the time, and that's why it starts in the cold without the choke.

 

[njmodi]

That is proof that the choke is working.

If it starts without the choke, that's probably okay. The choke isn't always necessary.

The only thing I can think of, is that the carb is adjusted too rich, and it's burning more fuel than it should all the time, and that's why it starts in the cold without the choke.

I thought about the last part - running too rich by default - but most new carbs are not even adjustable - at least not from what I've found. Even as far back as my Ariens, the main jet is not adjustable. Only the idle speed is adjustable.

 

[seepy83]

At this point, I'll just assume that it hasn't been cold enough to require the choke.

Since it's stored in my garage, maybe it's just "warm" enough that no Choke is required to start it. The garage isn't heated, and there's barely any insulation, but it is almost always above freezing in there. Even this morning after sub-zero temps outside overnight, there was water (not ice) on the garage floor/slab.

 

[smackababy]

At this point, I'll just assume that it hasn't been cold enough to require the choke.

Since it's stored in my garage, maybe it's just "warm" enough that no Choke is required to start it. The garage isn't heated, and there's barely any insulation, but it is almost always above freezing in there. Even this morning after sub-zero temps outside overnight, there was water (not ice) on the garage floor/slab.

That is most likely your issue. It is already warm enough to not require the choke, so using it isn't doing you any favors. The manual might (falsely) assume it is stored in the frigid cold temperatures, thus it would require a more rich start.

If it is starting without it, I'd say you're good just using it.