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

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.

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?

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.

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?

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.

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/brig...r-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.


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

.

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 ) Does anyone on the forum have experience from carburator renewal?

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.