# Stihl Trimmer Dying



## Chris616 (Dec 31, 2019)

A spark arrestor screen (outlet of the muffler) that is completely clogged with carbon can produce the symptoms that you describe. Here’s how to correct it.

Chris


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## kennykenny (Sep 23, 2007)

Chris616 said:


> A spark arrestor screen (outlet of the muffler) that is completely clogged with carbon can produce the symptoms that you describe. Here’s how to correct it.
> 
> Chris
> 
> https://www.youtube.com/watch?v=U-WgIikCVZs


I acquired this unit and it has no spark arrestor. I have previously checked for one.


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## Windows on Wash (Aug 30, 2011)

I would have guessed arrestor like Chris said.


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## DexterII (Jul 14, 2010)

With the die, wait, and then it starts scenario, I would check that the fuel vent. A plugged vent is like holding your finger over the end of a straw, creating a vacuum that stops the flow of fuel. If not that I would probably replace the carburetor.


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## joecaption (Nov 30, 2011)

Checked the air filter and fuel filter in the tank?
I like to check the cheap easy stuff first.
The carb's I buy on EBAY come with a new fuel and air filter, spark plug, fuel lines and only cost about $13.00.


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## kennykenny (Sep 23, 2007)

DexterII said:


> With the die, wait, and then it starts scenario, I would check that the fuel vent. A plugged vent is like holding your finger over the end of a straw, creating a vacuum that stops the flow of fuel. If not that I would probably replace the carburetor.


Where is the fuel vent?


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## DexterII (Jul 14, 2010)

Sometimes it's in the cap, and sometimes it's a separate device on the end of a fuel line, tucked in behind the tank.


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## SeniorSitizen (Sep 10, 2012)

If it has some age consider checking all those little hoses for cracks, especially where they bend and connect.


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## kennykenny (Sep 23, 2007)

kennykenny said:


> Where is the fuel vent?


sorry, I figured out the vent location


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## kennykenny (Sep 23, 2007)

I elected to go online and purchase a new carburetor kit after trying all of the suggestions given with no luck. This leads to a couple of other questions. In the kit, among other things, there is a black rubber grommet. Where does the grommet go? Secondly, I am assuming that even though the carburetor is new, it will need to be adjusted? If so, any tips/tricks on how to adjust it?

Thanks as always!


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## DexterII (Jul 14, 2010)

Kits often cover several different models, so the grommet may not be applicable in your case. What size is it? Is it possible that it goes on the back side of the air cleaner where it bolts to the carburetor? Most of the time the carburetor will be close enough that you can start it and then adjust it if necessary. You might find a setting in the manual, which you should be able to download at the manufacturer's site if you don't have it. If you can't come up with anything that way and still want to check it, 1-1/4 to 1-1/2 turns is fairly common. That's turns out from all the way in, but you don't want to force it, so just run it in gingerly with your fingers, or use a screwdriver if you have to, but just to where it stops. Don't tighten it. Then back it out. Either way, whether you want to try it before you get it started or after, I would count the turns in so that you at least have a starting point in case you end up with it where it won't start.


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## kennykenny (Sep 23, 2007)

DexterII said:


> Kits often cover several different models, so the grommet may not be applicable in your case. What size is it? Is it possible that it goes on the back side of the air cleaner where it bolts to the carburetor? Most of the time the carburetor will be close enough that you can start it and then adjust it if necessary. You might find a setting in the manual, which you should be able to download at the manufacturer's site if you don't have it. If you can't come up with anything that way and still want to check it, 1-1/4 to 1-1/2 turns is fairly common. That's turns out from all the way in, but you don't want to force it, so just run it in gingerly with your fingers, or use a screwdriver if you have to, but just to where it stops. Don't tighten it. Then back it out. Either way, whether you want to try it before you get it started or after, I would count the turns in so that you at least have a starting point in case you end up with it where it won't start.


Thank you!! When you say what size is it, are you referring to what size is the grommet?


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## DexterII (Jul 14, 2010)

Yes, the grommet. Specifically I was wondering if it was the size of the carburetor throat and, as I suggested, could possibly go between the carburetor and air cleaner. Otherwise I don't know where it might go.


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## kennykenny (Sep 23, 2007)

kennykenny said:


> Thank you!! When you say what size is it, are you referring to what size is the grommet?


No where in the shipping information does it state the exact size of the grommet. I measures across the top and it is 1/2 inch. Hopefully this helps.


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## DexterII (Jul 14, 2010)

Somebody else might be able to, but I can't help you with that one. Maybe where the fuel line passes through the handle or wherever, although it seems unlikely to me that they would give you that in a carburetor kit.


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## lenaitch (Feb 10, 2014)

When searching for your carb adjust question I came across a similar slightly older thread :


https://www.diychatroom.com/f29/stihl-fs56-rc-carburetor-adjustment-assistance-682985/


It seems replacement Stihl carbs come pre-set but if not, I found this -can't vouch for its accuracy:


https://www.hunker.com/12002532/how-to-adjust-the-carburetor-on-a-stihl-weed-eater


I think the grommets are for the fuel lines (main & primer) entering the tank.


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## kennykenny (Sep 23, 2007)

Following up on my original trimmer dying issue. I have replaced the carburetor, new fuel lines, new fuel filter, new gas. Still having issues. Upon installing the new carburetor , the unit started up right away. Ran for about a minute and then died. Could not get to restart. Waited about 5 minutes and the unit restarted. I let it idle for about 30 seconds and then pressed in the throttle and the unit revved up and then immediately died. Tried to start again right away and it wouldn't start. Did the 5 minute wait again and it started. Same issue, died when throttle pressed down. I turned the LA screw about one or so turns counter clockwise but it made no noticeable changes. I have not done any adjustments on the high and low screw yet since installing the new carburetor. 

I have also noticed that when the unit does start, the trimmer head is spinning with nothing pressed in. I thought that didn't spin until the the throttle was pressed. Correct??

After another five minute wait, the unit started up. Started fine. I let idle for about a minute and it sounded good. I revved up the engine and it did OK. As soon as I let off the throttle, the unit died. 

Ideas? Thanks.


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## DexterII (Jul 14, 2010)

As soon as it dies I would remove the spark plug, see if it's wet or dry, and check for spark.


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## landfillwizard (Feb 21, 2014)

Try running it with the fuel cap lose just to make sure there is no vacuum in the tank.


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## kennykenny (Sep 23, 2007)

DexterII said:


> As soon as it dies I would remove the spark plug, see if it's wet or dry, and check for spark.


Ill check for spark. Curious, wouldn't the unit have to have spark or the unit wouldn't;t start?


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## DexterII (Jul 14, 2010)

Yes, it needs both spark and fuel to start, and to run, which is the reason that I suggested seeing if it is wet when you remove it and then checking for spark. As I mentioned a week or so ago, a plugged vent, either in the cap or separate, will prevent air from filling the void left by the consumed fuel fast enough, so you create a vacuum in the fuel system and it runs out of gas. Then leave it be for a bit, the air slowly fills the void, and it restarts. Likewise, a coil that is failing will provide spark when cold, but loses it once it warms up. Hence pulling the plug, seeing it is wet, then checking for spark before the coil has a chance to cool down, and maybe point you toward one problem or the other.


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## kennykenny (Sep 23, 2007)

DexterII said:


> As soon as it dies I would remove the spark plug, see if it's wet or dry, and check for spark.


Latest update: The unit started the first time after sitting overnight(as it has been doing). Ran fine and revved up. As soon as the throttle was let off , it died and would not restart. 

I checked the spark plug soon after and the plug was dry. I checked for spark soon after and there was none. 

After sitting for for a bit the unit restarted. I opened the gas cap and left it open while the unit was running. I revved it up and let off the throttle and it died. 

Next thing to check? d


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## DexterII (Jul 14, 2010)

Okay, it should have spark, so that may indicate a problem. But how are you checking it, with a spark tester or by pulling the plug out and watching it? Either way you need to confirm that your benchmark is valid, so, since it sounds like it starts every time after sitting for X amount of time, I would leave it alone for a reasonable amount of time, then, instead of trying to start it, first check it for spark. The reason for this is to confirm that your tester is working, or, if maybe your ambient light is too bright to see it. In other words, you want to make sure that what you are seeing is actual versus an anomaly or whatever. Make sense?


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## kennykenny (Sep 23, 2007)

DexterII said:


> Okay, it should have spark, so that may indicate a problem. But how are you checking it, with a spark tester or by pulling the plug out and watching it? Either way you need to confirm that your benchmark is valid, so, since it sounds like it starts every time after sitting for X amount of time, I would leave it alone for a reasonable amount of time, then, instead of trying to start it, first check it for spark. The reason for this is to confirm that your tester is working, or, if maybe your ambient light is too bright to see it. In other words, you want to make sure that what you are seeing is actual versus an anomaly or whatever. Make sense?


I checking the plug by pulling the plug out and and using a piece of metal(long screwdriver) and grounding(touching) it to the engine and then touch the plug to the metal and pull the rope. 

I understand what you are saying about the light. I'll give it another shot. Thanks for responding.


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## kennykenny (Sep 23, 2007)

DexterII said:


> Okay, it should have spark, so that may indicate a problem. But how are you checking it, with a spark tester or by pulling the plug out and watching it? Either way you need to confirm that your benchmark is valid, so, since it sounds like it starts every time after sitting for X amount of time, I would leave it alone for a reasonable amount of time, then, instead of trying to start it, first check it for spark. The reason for this is to confirm that your tester is working, or, if maybe your ambient light is too bright to see it. In other words, you want to make sure that what you are seeing is actual versus an anomaly or whatever. Make sense?


Dexter, sorry you were right on the light issue. I checked again and there was a spark from the spark plug.


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## DexterII (Jul 14, 2010)

Okay, so now that you know what you need to do in order to see the spark, presumably you have or will start the engine, let it run until it dies, and immediately check for spark. You need to do it immediately because it won't take the coil long to cool down enough to start working again and flaw your test. Now, this said, the odds are, and my opinion is that the problem is fuel, not spark, but, since you have already changed the carburetor, it makes sense to at least check the spark. And assuming it is fuel related, I would go back and revisit what I think was my first suggestion, checking the vent because that's a sure and relatively common way to shut off the fuel flow. I would clean the cap, or, as someone else suggested, try running it with the cap loose. Also recheck that your carburetor mounting, throttle position, etc.


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## kennykenny (Sep 23, 2007)

DexterII said:


> Okay, so now that you know what you need to do in order to see the spark, presumably you have or will start the engine, let it run until it dies, and immediately check for spark. You need to do it immediately because it won't take the coil long to cool down enough to start working again and flaw your test. Now, this said, the odds are, and my opinion is that the problem is fuel, not spark, but, since you have already changed the carburetor, it makes sense to at least check the spark. And assuming it is fuel related, I would go back and revisit what I think was my first suggestion, checking the vent because that's a sure and relatively common way to shut off the fuel flow. I would clean the cap, or, as someone else suggested, try running it with the cap loose. Also recheck that your carburetor mounting, throttle position, etc.


I'll check again for spark. You mentioned thinking that it might be fuel. I have replaced the unit with brand new fuel right after installing the new carburetor. You mentioned checking the vent. I thought that I knew but when you said to check the vent, where is the vent located that I am checking? 

I did run the unit with the cap loose previously. I started the unit, while running, I loosened the cap and went through the same process and let off the throttle and it once again died. 

You mentioned throttle position, what is there to check there? I checked for throttle cable position and it seems set OK. I am assuming that there is only one way for the for the end of the throttle cable to fit in the carburetor mechanism? 

I previously asked, when the unit did start, before pulling the throttle lever, the rotating head was spinning. If I remember correctly, prior to the trimmer issues, the head didn't spin until the throttle was squeezed. Correct? I didn't know if this could have anything to do with my issues. Throttle issues? 

Thanks!!


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## kennykenny (Sep 23, 2007)

DexterII said:


> Okay, so now that you know what you need to do in order to see the spark, presumably you have or will start the engine, let it run until it dies, and immediately check for spark. You need to do it immediately because it won't take the coil long to cool down enough to start working again and flaw your test. Now, this said, the odds are, and my opinion is that the problem is fuel, not spark, but, since you have already changed the carburetor, it makes sense to at least check the spark. And assuming it is fuel related, I would go back and revisit what I think was my first suggestion, checking the vent because that's a sure and relatively common way to shut off the fuel flow. I would clean the cap, or, as someone else suggested, try running it with the cap loose. Also recheck that your carburetor mounting, throttle position, etc.


I started the unit and immediately checked for spark and there was a spark.


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## kennykenny (Sep 23, 2007)

I'm assuming that the pic is showing the vent that you are referring to. The hose is attached to the back of the air filter cover. I had replaced the hose, when replacing the carburetor. I noticed the filter, when setting it in the circular housing doesn't sit fully down. Is that normal? It lifts up a bit. Thanks.


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## kennykenny (Sep 23, 2007)

kennykenny said:


> I'm assuming that the pic is showing the vent that you are referring to. The hose is attached to the back of the air filter cover. I had replaced the hose, when replacing the carburetor. I noticed the filter, when setting it in the circular housing doesn't sit fully down. Is that normal? It lifts up a bit. Thanks.


I figured out this fuel vent. I didn't realize that it was two pieces and needed to snap into the circular housing. I got the pieces put together and snapped in. 

Tried starting again. Started up and ran but still died upon the release of the throttle. Good news, I was able to get restarted but the same scenario occurred. The unit died. Think the filter needs to be replaced? Something else?


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## kennykenny (Sep 23, 2007)

DexterII said:


> Okay, so now that you know what you need to do in order to see the spark, presumably you have or will start the engine, let it run until it dies, and immediately check for spark. You need to do it immediately because it won't take the coil long to cool down enough to start working again and flaw your test. Now, this said, the odds are, and my opinion is that the problem is fuel, not spark, but, since you have already changed the carburetor, it makes sense to at least check the spark. And assuming it is fuel related, I would go back and revisit what I think was my first suggestion, checking the vent because that's a sure and relatively common way to shut off the fuel flow. I would clean the cap, or, as someone else suggested, try running it with the cap loose. Also recheck that your carburetor mounting, throttle position, etc.


No new luck with the trimmer. The unit started today and ran for about five minutes and died. I never let off the throttle. Let it sit and couldn't get it to start. Sit a while longer and it tried to start and died. Ideas?


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## djlandkpl (Jan 29, 2013)

Some questions:
Is the throttle wide open just to keep it running? 
What position is the choke? 
Have you tried running it without the fuel filter?
The throttle cable slips into the carb. When the throttle is released is the cable loose on the carb connection?


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## kennykenny (Sep 23, 2007)

djlandkpl said:


> Some questions:
> Is the throttle wide open just to keep it running?
> What position is the choke?
> Have you tried running it without the fuel filter?
> The throttle cable slips into the carb. When the throttle is released is the cable loose on the carb connection?


Yes the throttle is wide open to keep it running. 
I start the choke at the top position on a cold start. Middle position on a hot start. When I squeeze the throttle, the choke moves all the way down to the bottom position. 
I have not tried running it without the fuel filter. I replaced the fuel filter a week or so ago. Should I try removing the filter and try? 

As far as the loose carb connection, can you please give further clarification? Are referring to the end of the throttle cable connection that fits into the carburetor circular mechanism? If so, I'm not sure what you mean by loose. Loose cable? It fits in the mechanism.

Thank you.


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## djlandkpl (Jan 29, 2013)

kennykenny said:


> Yes the throttle is wide open to keep it running.
> I start the choke at the top position on a cold start. Middle position on a hot start. When I squeeze the throttle, the choke moves all the way down to the bottom position.
> I have not tried running it without the fuel filter. I replaced the fuel filter a week or so ago. Should I try removing the filter and try?
> 
> ...



Try it without the filter. I had a blower that would only idle. Without the filter it ran great. I’m suggesting it to rule it out. 

For the carb connection, the throttle cable hooks into it. When the throttle is released the cable should have no tension on the circular piece...not pulling or pushing it.


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## kennykenny (Sep 23, 2007)

djlandkpl said:


> Try it without the filter. I had a blower that would only idle. Without the filter it ran great. I’m suggesting it to rule it out.
> 
> For the carb connection, the throttle cable hooks into it. When the throttle is released the cable should have no tension on the circular piece...not pulling or pushing it.



I started up the unit today after sitting overnight. Ran for about 5-10 minutes and then died during use even with the throttle pressed. it fades out much like a unit would do when something runs out of gas, without the sputtering. I removed the fuel filter and amazingly it started back up. Ran for less than 5 minutes and died and wouldn't start again.

No tension on the throttle cable.


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## hkstroud (Mar 17, 2011)

Suggest you check spark arrestor
https://www.youtube.com/watch?time_continue=17&v=U-WgIikCVZs&feature=emb_title


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## kennykenny (Sep 23, 2007)

hkstroud said:


> Suggest you check spark arrestor
> https://www.youtube.com/watch?time_continue=17&v=U-WgIikCVZs&feature=emb_title


It is an acquired unit. It didn't have and still does not have a spark arrestor.


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## djlandkpl (Jan 29, 2013)

As Dexter suggested did you check for spark once it dies? I'm thinking the timing is off but just a guess.


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## kennykenny (Sep 23, 2007)

djlandkpl said:


> As Dexter suggested did you check for spark once it dies? I'm thinking the timing is off but just a guess.


I did check for spark after it died and it did have a spark. The way that it dies while in use, it almost seems like it is a fuel issue but I am not sure what else to check.


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## djlandkpl (Jan 29, 2013)

I'm out of ideas except. Try running it with no fuel filter, loose gas cap and no air filter. It does sound like a fuel issue since you have to have the throttle on to keep it running.


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## Missouri Bound (Apr 9, 2011)

There is a point in every repair when a person reaches the limit of their capabilities. It looks like you have tried everything with no success.
Bring it to a repair shop if you want to keep the unit or sell it as it.
Somethings just can't be fixed with new hoses, carburetor, filter etc.
It does sound like a carburetor adjustment but since you changed the carburetor that is unlikely. Any chance you have bad fuel? I didn't see that addressed in this thread so maybe it is a factor. 
With the new carburetor it should run well. Since it doesn't perhaps it is a fuel quality issue. Too much oil in the gas or just gas that has just lost it's potential.
Have you tried fresh fuel mixed properly for that machine?


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