Export thread

Alright so let me run you through everything I have done to my dads Husqvarna 128LD.

First Round -
Clean the aftermarket carb my dad put on it last year.
Cleaned air filter and oiled it.
Used original gas lines and new ones of different size (thought the ones on it seemed a little on the big side for the little pipes coming out the carb).
Checked spark plug - practically brand new.
Cleaned spark arrestor.
Other greasing and cleaning that needed done

Second Round -
Put on new OEM carb.
Tried original fuel lines, new fuel lines of both the same diameter and a smaller diameter from the old ones.
Removed spark arrestor completely.
Put in fresh, ethanol free, 40:1 mix gas that works great in my chainsaws.
Tried running it with and without air filter.

Neither time did this weed eater have a fuel filter on the hoses.

HERE IS WHAT IT IS DOING -
I go through the suggested starting sequence. It seems to do ok but once I turn choke all the way off and its warmed up, I pull the throttle and it begins to rise in RPMs and then just bogs down and dies. It runs a little rough as it is. What could be the problem? I am stumped!

The OEM carbs are set from the factory to get it to start, but most of the time will need properly adjusted to run right. I am assuming this is the cube type carb with the recessed spline type adjusters correct. The adjuster wrench is out there but don't ask a dealer to sell you one because he can't.

So there's no fuel filter on the line? Is the fuel line floating?

As ILENGINE said these carbs are sent only tuned to a will start setting and must be tuned once installed. Also since you have been running the trimmer without a filter you may have clogged the carburetor's internal filter screen. It is a backup filter screen in case someone runs the engine without a filter and does plugs fairly easily. This to prevent internal clogging of the carburetor fuel passages. Depending on which version of this screen you may need to replace it as one version is not cleanable.

AVB said:

As ILENGINE said these carbs are sent only tuned to a will start setting and must be tuned once installed. Also since you have been running the trimmer without a filter you may have clogged the carburetor's internal filter screen. It is a backup filter screen in case someone runs the engine without a filter and does plugs fairly easily. This to prevent internal clogging of the carburetor fuel passages. Depending on which version of this screen you may need to replace it as one version is not cleanable.

Click to expand...

I haven’t been running it without a fuel filter. It has brand new oem carb on it and it didn’t work from the beginning.

The trimmer behaved the EXACT same way with two different carbs on it.One cleaned by myself, one brand new.

I am going to go out on a limb and say it is not carb related.

Have you removed the muffler and checked the piston for scoring?

Hammermechanicman said:

Have you removed the muffler and checked the piston for scoring?

Click to expand...

This is my next step.

PNC scoring normally affects the starting ability first as it lowers the starting compression below 100 psi.

With me repairing over a couple hundred these cubes what you describing is a lean burn problem; and unless, you re-tune the carburetor you never get it to run right. I see no where you have mention you tried tuning either carburetor. of the hundreds of cubes that repaired only one chainsaw with airhead carburetor had PNC damage that would allow it to start but not accelerate once tuned.

Now there is one other possibility not mention here in this thread and that is that the spark arrester could be clogged with can the similar symptoms as I have seen engines to start on choke then would run good at idle but fall flat on opening the throttle. Stilh 2 cycles are especially bad about this as they run richer than most 2 cycles.

On cleaning the carburetor how did you clean it; hopefully not with carburetor cleaner? They should only be cleaned using an ultrasonic cleaner with soap and water. Plus it preferable that the mixture screw(s) are removed to allow deep cleaning of the mixture passages. No probing allowed or excessive air pressure as it damages delicate check valves inside the cube. Even the carburetor cleaner can damage the rubber check valves. Then once a carburetor repair kit is installed the metering lever must be set to the correct height and both mixture screw lightly seated and out CCW 1-1/2 turns for the will start setting with fine tuning once the engine starts. L mixture is tuned first and then H mixture as they do interact with each.

Even a brand new OEM carburetor may need to be reworked too as I have seen the metering lever set incorrectly from the factory. Plus aftermarket carbs at one time were terrible and most still are about not working correctly. I got an aftermarket for a Stihl backpack blower that both mixture screws have absolutely no effect as they never was fully drilled.

So let me update you all. Forget everything I posted above.

This weed eater is starting just fine. Idling OK. and when given gas it slowly (slower than I think it should) revs up. It hits a certain audible RPM sound and then bogs out and dies. There is no saving it when it does this. You cannot pump the throttle, you cannot take your finger off the throttle. It just simply dies. It did this with both the old and the new carburetor. Exact same RPM, exact same timing, everything.

What I have done to it.

1. Brand new OEM carb. Misbehaved the EXACT same way as the aftermarket carb on previously before.
2. Muffler has been totally cleaned as well as spark arrestor that has been completely removed (worked the same as before it was off, same as after it was clean, same as after I completely removed it).
3. Brand new fuel lines.
4. Brand new fuel filter.
5. 102 PSI of compression.
6. Fresh ethanol free gasoline with a 40:1 mixture. I'd rather run it a little richer than to lean (I believe it calls for 50:1)

I checked the cylinder the best I could while the muffler was off. It looked good.

I am not a small engine mechanic. Obviously. I pretend to be one. I have never ran into an issue I couldn't at least diagnose what the problem likely is. This is getting beyond frustrating and at the same time, killing my pride of being a pretty dang good handyman.

I will look into getting the tool to adjust the carburetor. Again I am not a small engine mechanic, but I just feel like this is not the solution, but am totally open to trying it.

Thanks to everyone who has replied so far.

EDIT: I ordered a carb adjustment and cleaning tool kit on amazon. It came with like 8 different carb adjustment tools and some cleaning rods and brushes for like $12. Has the husky tool in the set.

Some remote thought. If this had the newer style variable ignition timing module with the built in rev limiter you could have a faulty ignition module also that could cause weird symptoms. Nothing like fighting a faulty module that never looses fire,but in your cause you could be loosing fire above a certain rpm.

DerekF said:

So let me update you all. Forget everything I posted above.

This weed eater is starting just fine. Idling OK. and when given gas it slowly (slower than I think it should) revs up. It hits a certain audible RPM sound and then bogs out and dies. There is no saving it when it does this. You cannot pump the throttle, you cannot take your finger off the throttle. It just simply dies. It did this with both the old and the new carburetor. Exact same RPM, exact same timing, everything.

What I have done to it.

1. Brand new OEM carb. Misbehaved the EXACT same way as the aftermarket carb on previously before.
2. Muffler has been totally cleaned as well as spark arrestor that has been completely removed (worked the same as before it was off, same as after it was clean, same as after I completely removed it).
3. Brand new fuel lines.
4. Brand new fuel filter.
5. 102 PSI of compression.
6. Fresh ethanol free gasoline with a 40:1 mixture. I'd rather run it a little richer than to lean (I believe it calls for 50:1)

I checked the cylinder the best I could while the muffler was off. It looked good.

I am not a small engine mechanic. Obviously. I pretend to be one. I have never ran into an issue I couldn't at least diagnose what the problem likely is. This is getting beyond frustrating and at the same time, killing my pride of being a pretty dang good handyman.

I will look into getting the tool to adjust the carburetor. Again I am not a small engine mechanic, but I just feel like this is not the solution, but am totally open to trying it.

Thanks to everyone who has replied so far.

EDIT: I ordered a carb adjustment and cleaning tool kit on amazon. It came with like 8 different carb adjustment tools and some cleaning rods and brushes for like $12. Has the husky tool in the set.

Click to expand...

Start it up and let it idle for a few seconds. With one hand on the throttle, and another on the choke, as you squeeze the throttle til it starts to die, rock the choke on and off pretty fast.

If it's doing the same exact thing on two different carbs, than I understand what you're saying about it not being a carb problem. But bogging down, when you squeeze the throttle is a carb or compression problem.
If you have good eyes and a very small high beam flashlight, you can also look down in the cylinder through the spark plug hole and sometimes see a lot more of the cylinder.
I'm not sure what type of compression tester you used, but as @bertsmobile1 has pointed out to me a few times now, compression testers are no accurate. But they do give you some idea as to whether its got compression or not.

But try the choke trick and report back. Everything you're saying makes me think it's a carb problem. Except for having different carbs on it, and it still doing to the same thing.

BTW, When you do throttle it up, does the head turn at all? Just thinking something could be bogging the engine down.

5. 102 PSI of compression.
Failure of test. Stuck Ring or PNC Damage

ILENGINE said:

Some remote thought. If this had the newer style variable ignition timing module with the built in rev limiter you could have a faulty ignition module also that could cause weird symptoms. Nothing like fighting a faulty module that never looses fire,but in your cause you could be loosing fire above a certain rpm.

Click to expand...

I was wondering this at one point, I am going to look into it as a possibility. This machine is just so basic that I would be surprised if it has than, but I appreciate the comment. Ill let you know what I find.

PTmowerMech said:

Start it up and let it idle for a few seconds. With one hand on the throttle, and another on the choke, as you squeeze the throttle til it starts to die, rock the choke on and off pretty fast.

If it's doing the same exact thing on two different carbs, than I understand what you're saying about it not being a carb problem. But bogging down, when you squeeze the throttle is a carb or compression problem.
If you have good eyes and a very small high beam flashlight, you can also look down in the cylinder through the spark plug hole and sometimes see a lot more of the cylinder.
I'm not sure what type of compression tester you used, but as @bertsmobile1 has pointed out to me a few times now, compression testers are no accurate. But they do give you some idea as to whether its got compression or not.

But try the choke trick and report back. Everything you're saying makes me think it's a carb problem. Except for having different carbs on it, and it still doing to the same thing.

BTW, When you do throttle it up, does the head turn at all? Just thinking something could be bogging the engine down.

Click to expand...

Today I tried your choke trick, when this engine bogs out and dies, it very quickly bogs out and dies, there isn't much time to try and stop it and I haven't successfully manipulated it to stay running. It immediately dies every time.
As for the head turning, no. It like intermittently starts and stops, not necessarily with how fast the engine is cranking. I should have thought to mention this before. I took the whole shaft assembly off the motor end of the trimmer and spun it with my finger. It spun very freely. If this is related, its got to be up in the clutch area I am thinking? The trimmer head behaves some what oddly when giving it more gas.

AVB said:

5. 102 PSI of compression.
Failure of test. Stuck Ring or PNC Damage

Click to expand...

What is PNC damage? What would indicate a stuck ring as far as sound or bahavior?

Are you still running it with no fuel filter? You need to make sure the fuel line is submerged in gasoline at all times and the filter weights it down.

Darryl G said:

Are you still running it with no fuel filter? You need to make sure the fuel line is submerged in gasoline at all times and the filter weights it down.

Click to expand...

In my update I wrote that I had a new fuel filter on it. Its submerged. Still not running right. Its my dads weed eater and I have been making lots of extra little cash fixing broken small power equipment and selling it. Since I have had so much success I am considering trying to do a little small engine repair on the side, so this was extra practice before putting myself out there like that. He didn't have a fuel filter on it, I was trying to get it going without spending any money since its not a paid job, and i'd just put one on after I got it working, since you suggested putting one on it, I decided I would. So there is one on it now. This is a humbling experience to help me realize I probably have a ways to go before advertising as a small engine mechanic.

DerekF said:

In my update I wrote that I had a new fuel filter on it. Its submerged. Still not running right. Its my dads weed eater and I have been making lots of extra little cash fixing broken small power equipment and selling it. Since I have had so much success I am considering trying to do a little small engine repair on the side, so this was extra practice before putting myself out there like that. He didn't have a fuel filter on it, I was trying to get it going without spending any money since its not a paid job, and i'd just put one on after I got it working, since you suggested putting one on it, I decided I would. So there is one on it now. This is a humbling experience to help me realize I probably have a ways to go before advertising as a small engine mechanic.

Click to expand...

Ok, sorry missed that.

I run Husqvarna trimmers for my lawn care business. I had one of those trimmers and it's a low-end model that don't tend to be very long-lived. They're kind of heavy and clumsy for the power they provide as well. I gave mine to my son for the small lawn at his apartment and wont miss it. The 223, 323 and 326 are much better units. I'm running a 525 most of the time now but still like the light weight of my 323.

I think that unit has already been more trouble for you than it's worth honestly.

DerekF said:

In my update I wrote that I had a new fuel filter on it. Its submerged. Still not running right. Its my dads weed eater and I have been making lots of extra little cash fixing broken small power equipment and selling it. Since I have had so much success I am considering trying to do a little small engine repair on the side, so this was extra practice before putting myself out there like that. He didn't have a fuel filter on it, I was trying to get it going without spending any money since its not a paid job, and i'd just put one on after I got it working, since you suggested putting one on it, I decided I would. So there is one on it now. This is a humbling experience to help me realize I probably have a ways to go before advertising as a small engine mechanic.

Click to expand...

I know what you mean. That's how I started out a few years ago. And still starting out. Getting hung on one trimmer you can't figure out, is nerve wracking. To say the least.
This is a little off topic, but I got a throw away brand running once. As far as my compression tester could tell, it had over 100lb. And after getting it running good, I sold it to someone who brought it back the next day. I cleaned out the carb, tuned it up and it was running great again. So the customer came back and got it. Called me the next day with the same problem. So I just gave her her money back.
Repeated the same process again, and I still have it. It still runs good.

But back to your problem. I'm at a loss.

Does it idle ok? Can you crank it up and just let it sit there and idle for long periods?

Before you start adjusting it with your new tool, turn each carb's screws in (clockwise) until they seat & count the revolutions. Put a paint mark or something on the handle so you can have a reference. Should be 1 1/2 to 2 turns. If not, maybe that's the problem; ie, they were set wrong or perhaps too lean at the factory. Then, as AVB advise, turn them back out 1 1/2 turns, start it up & try tuning the carb with your tool. If it still fails, you might want to try 2 turns out for starters since your issue is that it bogs when you give it more throttle. Wish I could give you more, but often it is just requires a lot of patience, trial & error, & a good ear.

Thanks everyone for all your comments and time. It's been a frustrating little job and I never figured it out. I did the screw adjustments on the carb, screwed all the way in, then backed out 1.5 turns and tried to tune it it from there. It never changed anything. I appreciate everyones thoughts.

Question for those small engine mechanics out there. If you run into issues like this, where you just can't figure it out (if that ever happens to you), what do you tell your customer? Also, at what point do you tell your customer that the machine just isn't worth fixing?

Just read through the entire thread and I’m wondering if you checked the crankshaft seals? If one of the seals has a slight crack, it will allow air into the crankcase, creating a lean mixture.

Well....... Have you tried starting it without the muffler attached. What you you describe is a classic plugged up exhoust. You have messed with carbs enough to say may not be a carb issue. If that is a piston port engine (most are) not a whole lot to go wrong if you have compression and spark. Air and fuel in and noise and hot gas out. Sounds like you have air and fuel in. If the muffler is plugged it will start and idle but bog and die when you throttle up.

I pull the colortune out of the toolbox
Set it up & set up the video camera .
Then tape the results till the engine stops

the engine behave like this when you get low on gas in the carburetor, do you have a fuel pump on this machine?

Doggydoggen said:

the engine behave like this when you get low on gas in the carburetor, do you have a fuel pump on this machine?

Click to expand...

My lord do you even know what the 128 LD is? And to answer your question; Yes he has a fuel pump it is built-in the carburetor as nearly all cubes and rotary carburetor do. I actually have not seen without a fuel pump.

I am having the same exact issue. New gas lines,new carb, cleaned the muffler. Will run fine but if revved up will just quit like some out turned off the gas.

Slightlychilled said:

I am having the same exact issue. New gas lines,new carb, cleaned the muffler. Will run fine but if revved up will just quit like some out turned off the gas.

Click to expand...

You will do a lot better to start your own thread.
Read through the answers here, try them on your tool the post the results so we know what you tried & what the results were
We also need to know what we are dealing with, make & model numbers please.

bertsmobile1 said:

You will do a lot better to start your own thread.
Read through the answers here, try them on your tool the post the results so we know what you tried & what the results were
We also need to know what we are dealing with, make & model numbers please.

Click to expand...

Why would I start a new thread when my experience ,model and problem are exactly the same as the OG post.

Husqvarna 128LD FIXED!
Tell u what this has been a fun little nightmare.
First: put fresh mixed gas in, pulled plug cleaned with wire brush and replaced.. primed, pulled, fired right up for a few seconds then buuuggghhhh. Bogged out. That's when the fun began.
Next: picked up a new plug that evening while I was in Wallyworld. Next morning installed new plug checked air filter (it was pretty gnarly but got it cleaned up enough that maybe it would stay running. Nope!
Now I'm tired of messing around so I pull carb, break everything down, clean with carb cleaner, reassemble, replace fuel lines, fuel filter, picked up new air filter from Lowes, can of Husqvarna 50:1 premix fuel, checked exhaust screen, put everything back together and same thing.
At this point I was teetering between actually listening to my wife and just blowing $200 on a new one.. or giving it one more shot. And I'm not giving her the satisfaction of "i told ya so" lol. Last ditch effort...replaced the spark plug...and that did it! Turns out there is an odd problem. Make sure that you have a resistor type plug installed. The electric field generated by a non-resistor plug can interfere with the ignition and emulate a stop signal to the trimmer when it's wide open. Never knew that before. Hope that helps! Oh, and I have less than $30 invested and it runs like a beast.

OK, thanks for that... gonna head out and get a spark plug and see what happens. FYI, I have the exact same issue, have rebuild the carb, replaced lines/filters, checked the spark arrestor, etc. When new it worked great, but after only a year or so developed this issue where it will not take throttle. Idles fine, revs up if you give it maybe 10-20% throttle, any more and it dies. Carb adjustments don't fix. The interesting thing I've found is that when the unit is cold (i.e. been sitting all night), it will go full-throttle just fine after a brief warm-up. It *only* starts this bad behavior after it gets hot.

AND, apparently that fixed the issue, as unlikely as it seems. Replaced the original (not very old) RCJ8Y with a Champion 843ECO, problem gone!

My 128 was stalling when throttling up, very typical of the many complaints I've read. Like many owner i replaced and cleaned every part removable and it continued stalling. I removed the new carb i had replaced and inspected the gasket between the carb base and engine wall, it had a small tear, i replaced the gasket and viola! That 8 year old machine runs like new. I don't believe all those old parts replaced with new ones was necessary.

i have the same weed eater and i have the same problem. The answer i got from the dealer is that model is known to have this issue and they no longer work on them due to the poor quality that it came from the factory with problems. If anyone has found the fix for this it would make alot of people happy includeing me. i have no clue what to do next. i have also done everything he did and i adjusted the carbs both the rebuilt and the new ones.

Find a new dealer ,
Hand held 2 strokes are dirt simple in operation & in repair
Like many shops their repair cost probably exceeds the replacement cost
I don't like working on single ring engines because that single ring has to do way too much work
So they tend to wear quickly and replacing a piston rung has a higher labour charge than the replacement costs
Apart from correctly adjusting the carb and fitting new gaskets you really have very little else to prevent it working
When I first started repairs was new to cube carbs & the previous owner was big on fitting new D & G kits.
A couple of years down the track I learned the proper way to do it
And that starts with pressure & vacuum testing the fuel tank, then fuel lines, then carb then crankcase seals, then rings.
Flow testing the carb consists of sliding it off while still connected and blowing high volume low pressure air through it , checking for a strong atomised fuel flow out the engine end.
Since then I have fixed so many "unrepairable" trimers because they had a faulty fuel cap .
2 strokes will tell you what is wrong all you have to do is listen
If the engine note gets harsher & higher pitch that is the engine telling you it is running lean
If the note gets lower , breaks up a bit then goes soft & stops then it is too rich
If it just shuts off which no change in the exhaust note then it is electrical .
Hard to start cold but will restart no problems when hot points towards leaking crank seals
The trick in not going mad is to work out why it is failing first rather than do as the first poster did and fit a bucket load of new parts particularly if it was an EvilPay AmmoZone "tune up kit" many of which are an assembly of defective parts .Read the whole thread
1) Henry , had a leaking manifold gasket ,,,,, Fixed
2) Danmasi bad spark plug,,,,,, Fixed
3) Hold my beer Bad spark plug,,,,,Fixed
4) Dereck no fuel filter to hold the fuel line down so was sucking air,,,,,,Fixed

The only common thing is none of then understood how these engine work .

So which one of these problems have you decide is exactly the same as yours ?