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Discussion Starter #1 (Edited)
I have 10 year old Husqvarna 8024STE with a 15a100 series (15a114-0732) B&S engine on it. I am happy with the machine itself, but over the years the mixture has gradually become leaner requiring me to run it with choke from 1/4 to 1/2 on just to prevent it from stopping under load.

Understanding that there is a mixture problem I have taken the carburator apart (several times) to clean the carburator itself as well as the main jet. Only minor improvement in the performance has been achieved after cleaning (When I clean the carburator I use carb cleaner, pressurized air and needles for the holes and the jet. I must also mention that the carburator looks nice and clean without any corrossion or deposits inside before cleaning). Other actions I have tried to fix the problem:

-Valve adjustment carried out
-Confirmed unrestricted fuel flow from tank to carburator
-New spark plug
-Fresh gas is used
-Rubber gasket between carburator house and engine renewed to rule out false air leakage.

I do have mechanical training and it irritates me a lot that I cannot get around this problem. It reduces the power of the machine as well. It also irritates the heck out of me that B&S built this engine without any possibility to adjust the mixture on the carburator.

Any forum members with experience on how to proceed here is much welcomed.

Greetings from Norway :wavetowel2:
 

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Welcome to the forum! Especially for someone so far away :)

Do you have access to an ultrasonic cleaner? Perhaps it could help clean something that the manual cleaning hasn't been able to remove?

To make an engine run richer, some people have installed larger jets on carbs that have them available. Or drilled out the jet slightly using a set of micro-drills. This can help with an engine that was running lean from the factory. But in your case, it started better, and has gradually gotten worse over time, which makes me suspect that something is still dirty/clogged, rather than the jet being too small originally.

You don't have something like an air leak around the throttle shaft, or somewhere else on the engine, do you? I have sprayed carb cleaner (or something else, make sure it won't damage paint/rubber) at areas of engines while they're running to listen for changes. If there's an area that should be sealed up, but the engine sounds different when you spray something there, you may have an air leak. Admittedly, if the area is near the intake, some spray can be drawn into the intake, giving misleading results.
 

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Discussion Starter #3
Before changing the thick rubber gasket between the carburator housing and the engine I sprayed with start spray and noted different engine rpms. Thats what led me to changing the mentioned gasket. But honestly I think that there was no false air leaking, it was just me who was to generous with the spray. If I am carefull with the amount of spray I cannot note any difference in engine rpms now at least.

One thing I have noted is that I have tightened the main-jet (which is also the bowl bottom plug) a little tighter than original resulting in that the bottom of the bowl was squeezed in a little. I have carefully dented the bowl out again using a big socket as a rest and a smaller one as a rammer. So there may be minor differences in the shape of the bowl compared to what it is originally. However I cannot see that this should interfere with the fuel flow and more important the problem arised while the bowl still had it`s original shape.

I do not have access to ultrasonic cleaner.

I can see that a new main-jet is not expensive at all, and I am wondering if I should give it a try. But on the other hand I cannot see anything wrong with the one I have on hand. Drilling the main-jet... well that seems risky to me. I guess it wont take much to end up with a to rich mixture. I also only have a hand held drilling machine. Hitting the right diameter and correct mixture on those small engines must be like playing the lottery. Any experience on the forum on this proposed sollution?

Any other ideas or experiences on the forum? Does anyone have experience with renewing the main-jet with a new one or renewal of the entire carburator?
 

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I've heard that if the float is at the wrong height, it will affect the mixture. Presumably (!) if the float was keeping the fuel level in the bowl too low, then engine would run leaner.

Have you checked the height that the float sits at? The Tecumseh service manuals list a procedure for checking this, I don't know about Briggs.

I would check the other possibilities before drilling out the jet, especially if it ran properly when new. Given that it was OK originally, the only reasons to drill it, I would think, would be if cleaning it wasn't removing something, or maybe if it had corroded slightly, making the hole smaller. But otherwise, opening the jet might just mask the real cause.
 

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Discussion Starter #5
I don't have a procedure for checking the float height properly, but it appears to be correct and I doubt the minor change of the bowl shape makes any difference for my problem.

I have been thinking that there may be corossion inside the jet and other lines in the carburator. Especially since the lean mixture problem appeared gradually over a few years. To properly remove that I would need tiny brushes. Is there a place to buy that? I only have needles now. Or would it be cheaper to buy a new carburetor or jet?
 

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I don't know about jet or carb costs for that engine, sorry.

I know some people use copper wire to clean out passages. It's softer than needles, so maybe you could "scrub" a little harder, while still reducing the risk of damaging things. I've also seen people talk about using the wire from the twist-ties used on bread packages, etc.

I was going to buy a new carb for my generator ($50-60), then thought about it some more, and bought an ultrasonic cleaner instead. I've used it to clean 3 carbs already, so I suspect it will end up saving me money in the long run. Plus it may be able to help clean areas that are difficult to reach.
 

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What I found is the B&S carb for your engine should be a #590907

It's #125 in the list.
https://www.partstree.com/parts/briggs-and-stratton/engines-horizontal-engine-with-electric-starter/15a114-0732-e1-briggs-stratton-engine-electric-starter/carburetor-fuel-supply/

That's been replaced by P/N 594014. Not sure what you'd pay but over here in the U.S. it's available for $50 plus some shipping.

Briggs Stratton Carburetor 594014 Replaces 590907 798918 794588 | eBay

If you can't get it clean then it might be time to replace. :blush:

.
 

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Discussion Starter #8
Thanks. I have evaluated a new carburator and if I knew that would fix the problem I would order a new one right away. However, using Google the last few days have given me the impression that even a new carb necessarily wont fix it. (Even new carbs are set lean to meet US EPA regulations, and B&S has taken away the mixture needle because they believe their customers are not smart enough to operate it :icon-hgtg: ) Does anyone on the forum have experience from carburator renewal?
 

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What do you mean by carburetor renewal, exactly? Replacing the jet? Installing a rebuild kit with new seals, needle valve pin, etc?

Some people have mentioned buying adjustable needle retrofit kits for Honda-clone engines, I think, on eBay. Is anything like that available for your carb, perhaps?
 

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Discussion Starter #10
What do you mean by carburetor renewal, exactly? Replacing the jet? Installing a rebuild kit with new seals, needle valve pin, etc?

Some people have mentioned buying adjustable needle retrofit kits for Honda-clone engines, I think, on eBay. Is anything like that available for your carb, perhaps?
I mean replacing the whole carburetor. Thinking loud: Replacing the existing carburetor (fixed lean) with a new one (fixed lean) may not solve the problem. Maybe a wear pattern or tiny disturbance from production causes exactly my engine to develop this particular problem after a certain amount of years. I may sound difficult now, that is not my intention. Therefore I am interested in listening to other peoples experience after either replacing the jet or the complete carburetor after their engine was starting to run lean. On the internet it appears that this is a quite common problem for both B&S, Tecumseh and even some Honda engines.
 

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If you were in the US, you could get a new HF 212cc engine for cheap. But I'm guessing options in Norway are more limited.

The link you posted then links to a thread on another site, with a long discussion:
Sears Craftsman Snow Thrower Dying - DoItYourself.com Community Forums

I didn't read through all of it. There are a lot of people with similar symptoms, it seems. Starting, running for a period of time (like 15-30 minutes), then getting weak or dying. But those don't sound like the same symptoms as what you're describing, unless I misunderstood. The common theme I'm seeing in that thread is essentially that many problems are runtime/heat related. Not necessarily progressing over the span of years.

There was a suggestion that seemed worth checking, to me: have you checked your valve clearances? I'd imagine you might see backfiring in this scenario. But if a valve was staying open slightly, it might let some of the fuel/air mixture out before firing? I suspect this would be more obvious if a valve was staying open. But checking the clearances is probably fairly easy.

There were a number of other suggestions that I noticed as well, of course. Building a heat shield, plugging the gap around the choke knob, disconnecting the kill switch, etc. You could look into those, if you thought your symptoms were related.
 

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Discussion Starter #13
After hours of reading I have decided to try out a new replacement carburetor. My Husqvarna 8024STE is old, but it has been well maintained and is still to good to be dumped. One of the more interesting threads is this one: http://www.snowblowerforum.com/forum/craftsman-snowblowers/13225-stalls-when-wet.html. This thread is about a Craftsman blower, but they have the same troublesome B&S 8,5HP engine (Engine ID: 15A114-0732-E1). The bottom line of the problem is that the engine stalls due to fuel starvation. If it is caused by icing, restricted carburetor jet flow or fuel heat lock is intensively discussed on the internet. Now lately I tend to believe that there is a connection to icing. My problem worsens a lot when it is either cold and windy with dry snow in the air or when it is relatively mild with wet air. Both conditions allow for moisture to be ingested in the carburetor. Also, if my engine first stops (me not being able to keep it running by closing the choke quick enough) it takes 30 min+ before I am able to restart it. I have always wondered a lot why it took so long, but icing may be the answer.

The original B&S carburetor P/N is 794588. This was superseeded by P/N 590907 which again has been superseeded by P/N 594014. I will try to take pictures of the upgrade and post as well as my experience once the carb is fitted and tested under the right conditions.
 

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I think you will find that new carb was re-designed for a reason and will probably fix your trouble.... lots of guys have chased their tail on that one from the reading I have done and that's what fixed it. Good luck! Let us know.....
 

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Discussion Starter #15
I think you will find that new carb was re-designed for a reason and will probably fix your trouble.... lots of guys have chased their tail on that one from the reading I have done and that's what fixed it. Good luck! Let us know.....
So far I was only able to find one guy who solved the problem with a new carburetor, and another one (see my post #11 above) who didn`t and went on with a new engine.

Can you please post links to those who solved the problem with a new carburetor? I am very interested in reading their experiences :)
 

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Mmosberg: As noted above by bad69cat, I chased my tail for 1 year on this problem, till I found the post by conwaylake regarding the probability that carb icing on the Briggs 8.5 hp was the root of the problem. My symptoms were identical - would stall when exposed to wet snow or blowing snow in a high wind. Once it thawed out, it would start right up. This sounded like carb icing. I tried complete dismantle and cleaning of carb and jet holes to no avail. Once I read conwaylake's thread, I ordered the replacement carb from amazon (apparently it is about 4 generations improved). It comes with all you need including a heat shield for around fuel line, etc. Once installed, my blower has completely trasformed. We had a blizzard in Nova Scotia last weekend and the machine did not stall once in high winds and snow (30 cm). I believe conwaylake has had the same success. It appears this new carb is not affected by icing, the way orig carb design was. As with anything, individual results may vary, but for a modest investment of $50.00 for the replacement carb, I think this is your best shot. By the way conwaylake has an excellent how to install in the thread "stalls when wet" you quoted. Best of luck - has it been a snowy winter in Norway?
 

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Discussion Starter #17
cargy2003. Thanks for your nice contribution. I have now ordered a new carburetor and will pick it up next week. I noticed that the replacement carb now has B&S P/N 594014, while when conwaylake did the upgrade (and you?) the B&S P/N was 590907. I hope and believe that the new carburetor will be a permanent fix to the problems. Searching the internet convince me that there is serious design flaw in those Briggs and Stratton 15A100 series engines when I see how many people who are struggling with more or less identic symptoms. Not that I expect any compensation, but I think that Briggs and Stratton as a minimum should publish some information on their internet pages around this issue. But by doing so they would admit responsibility so I guess that wont happen for obvious reasons. There are probably thousands of snowblowers with this type of engine and equally many swearing owners around the world. The **** thing start to trouble when you need it the most.

The winter over here has been quite snowy. I live in the very south part and here it is quite normal with storms and wet snow. This winter however gave us 3 freezing weeks in January with dry snow. Actually it snowed every day for a week just after newyear and it was down to -18 Celsius (0 Fahrenheit). This weather caused worsened problems for my snowblower when ingesting moisture/snowcrystals. I hope for some realy provocative conditions after I have installed the new carburetor. Then I will get to know if it works. Anyway I am so pleased with the help on this forum that I was planning to post a few pictures together with a step by step story when I change the carb. And I will also let the forum know if it worked. Cheers :)
 

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When you get the new one, do a post mortem on it along with the new one and note all the differences you see..... I am curious to what they changed and what you might be able to do (if any) to the original to remedy/fix those? Xing my fingers!
 

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I cant remember how I tracked it down on the net, but several years ago I was able to find a carb for my Toro made by Oregon that had the adjustable jets. Was so glad too find it and wasn't overly priced. Cant remember how much but I was ready to pay almost anything for it.
 

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Discussion Starter #20
Got the replacement carburetor delivered today. Disappointment: On the fitting instructions there is a large WARNING triangle with the following text: The carburetor must be fitted with an intake arrestor! There never were an arrestor on my blower. Nor was there any info about this on the B&S maintenance replacement parts site.

1. What is normal on B&S snowblower engines. Are they with or without intake arrestors?
2. Should I obtain an arrestor, or can I proceed without?
 
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