How to clean, adjust, and fix common carburetor problems on a Stihl FS90 trimmer weedeater
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- Опубликовано: 29 янв 2017
- We have been using several Stihl FS90R trimmers for years now. We currently use 10-12 trimmers divided among crews each year. I have found 2 common problems with these trimmers and would like to show you how to fix them. One problem is that there is a little screen inside the carburetor and after months of use, debris builds up on this screen and must be removed. I'll show you how to take apart the carburetor and clean this screen. The 2nd problem is that the carburetor needs adjustment. There is a high and low speed screw on the back of the carburetor and if your trimmer is running rough, or there is erratic idling, popping, or difficulty keeping the trimmer running, you can adjust the low speed screw until the trimmer runs smoothly. I've seen different types of carburetors on the FS90 trimmers. Some have adjustment screws that require a screwdriver and others require a hex driver or 5/32 socket. The adjustments to each of these carburetors are different. So it's best that you let your trimmer warm up and adjust the Low Speed screw slightly until your trimmer runs smoothly.
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Why is it that you are the only person on RUclips that knows exactly what to do ? You are a legend ! Thank you so much .... I wasted so much time watching all the other dumbshits harping on about the spark arrester ! Keep up the good work 👍
Thanks for the kind words.
Nice video so many guys on here know even less than nothing.you know everything.as a commercial grounds maintenance worker. With my own company these types of videos are invaluable.one guy on here took 56 minutes to do what you did in 15
actually the spark arrester is a fairly common problem. so you shouldnt judge everyone. you obviously dont know it all either.
Same here lol
Hey Mike, this is Stihl FS 90 R ? right? Could you tell me Please, what's the part number for this carburetor? Thanks!
Possibly the most productive 7 minutes of any video I've watched. Succinct, no distracting musak and I now have a fully working trimmer. Manythanks for your time and effort from a grateful viewer in Southern France.
Mewsack
Bit of a necropost but just found this and fixed our strimmer in 20 mins! Fab vid. Simple, straight-talking. Thank you so much!
Awesome. I'm going to start stalking you now. My dealership is beyond awful. I have to write Stihl. It's such a disgrace. Thank you for your videos to teach people like me who don't know a single things about mechanics.
Thank you! I’ve always been a little intimidated about diving into the carb on a weed eater. I was about to take mine in for someone to repair it and decided to try cleaning and adjust carb first. Adjustments fixed it :) great video
Nice vid:
* Smooth camera work.
* No obnoxious music
* Clear sound.
* Good lighting.
Sherwood Botsford and he gets right to the point unlike most people who spend 6 minutes talking about stuff we don’t care about like they are tv celebrities
I second your comment about no music. He is good. I make videos and he is good
Finally a video that just gets to the root cause without all the other stuff...
Thank you for posting.
First thing to say is thank you. Second is what a great demonstration and explanation. Really glad I found this and appreciate the expertise shared by this guy. He is excellent and obviously expert. Best video on this topic I have seen.
I was having a hard time with my fs86 starting, idling and running. I cleaned the carb and the "screen" and it runs quite well. Especially since I used 100 octane aviation gas. Thanks for the upload, sure helped me a lot. Thanks again.
Hi Mike, thanks for your video! Even though it was made five years ago I am hopping you still monitor your viewer's comments as I have a issue with my Stihl FS 90 weedeater.
First, I recently had it at Steve's Honda for seasonal maintenance, new in-tank gas filter, over all cleaning and adjustments. I have used it 3 times since I got it back.
It starts first pull usually, second for sure. Runs normal for about 5 to 10 minutes then looses power and runs about 1/3 speed at full throttle.
After watching your video I accomplished the same. I found no build-up at the carburetor screen but removed it and sprayed it out with carb cleaner. Even though I know there is only maybe 5 hours on the new tank filter I removed it and back sprayed it anyway. It too was clean. After reassemble it started on first pull this time ran great for about the same as before then dropped down to 1/3rd speed at full throttle.
While it was still running I had an idea to reach around and pump the prime bubble. It worked, for a short time then pressed about half down every minute or so to finish clearing the small area I started on. Eventually, I double-pumped the bubble to see if it would run longer and flooded it. This time it would not restart due to flooding, and I was done with it running that way and did not clear the flood situation.
I run non-Ethanol fuel with 76 2T Unimix 2 cycle oil.
What am I missing or overlooking? Thank you for your time in responding.
You may have figured this out already but I'm pretty sure you have a partially clogged tank vent. On the Stihl trimmers, the vent is usually a hose connected to the back of the air filter holder, and you'll see a tiny hole on the air filter cover. As fuel in the tank is used, air must replace it to keep from building a vacuum in side the gas tank. If the vent is clogged, it will run great for a few minutes, but as fuel is depleted from the tank, more vacuum is created inside the fuel tank and the carb can't get the fuel it needs. To verify this is the issue, next time it you use it, once it cuts back to 1/3rd power just unscrew the gas cap and see if it suddenly starts running normal again. Then you just need to clear the clog in that vent, very simple fix if that's what it is.
Couldn’t get mine to work. Followed these directions which were great. My screen was already clean but I cleaned everything else. Started up and works now. Not sure where the problem was but it worked! Thanks!
Same comments as others have said, you don't waffle and so easily and not filled with bullshit jargon and unnecessary shite, and I followed this step by step and resolved the pain in the arse that was causing me all sort of kak!!
You have been one of the quickest subs I have done and that's cos of yr no nonsense waffling to fill time and inevitably makes us watching switch off as some people like the self sound of importance, but you are a lifesaver and nearly 8 painstakingly watching other videos, this was the help needed before I was gonna launch the fucker in the skip!!!
Thank you...Thank you....Thank you!
The screen on my carb was not plugged, but the great instructions made it relatively easy to take it apart and blow out all the passages with carb cleaner. Runs great now, thank you!!
Thanks for the tip. I've been having problems with my Stihl FS38 brushcutter and you've taught me how to fix it. Greetings from the former Australian Territory of Papua New Guinea.
I am about to replace the carb on my FS90 tomorrow and your video is a great guide.
When that small screen is cleaned and all goes well replace fuel line filter. Often the debris is from a fuel filter deterioration. Mr. Miller is correct in that this problem is common. Good advice Mike!
Thankyou Mike great clear instructions,i run my own small garden business here in england and thanks to people like you i can service my own equipment and save a few quid in the meantime.
Thanks Mike - very clear, succint, straightforward guide. You're a natural!
Well done! Found a million other spark arrestor videos before I finally found this one.
This will be the first video I have ever subscribed to! Clear and to the point.
lol, those fucking spark arrester videos are a pain in the arse !!
Thank you for giving good explanations about common problems.
Very helpful, thank you for getting right to the point and explaining everything! Cleaned my screen, carburetor and changed spark plug and my FS40C is running great!
I was running this saw for about 2 hours at about a 30-50% duty cycle ruclips.net/user/postUgkxfQm1wmg0ItKDLavxj1nXtQY9HP7EF504 and it did a great job. I used the lever for the built in sharpener to clear chip buildup out more than to actually sharpen the chain. It managed to cut some hardwood stumps much larger than it's size without bothering the neighbors with hours of 2 stroke noise.
Thank you for not just telling me to clean the carbon out of my exhaust screen. . great video!
lol! I feel your pain brother.
Solid video, I wanna pay you for watching this it was so perfect. No bs and exactly what people need to learn.
great video ! I like to see if I can see light through those screens after I clean them , you would be surprised at how many of them look good but if you hold it up to a light you see nothing , you must be able to see light through those screens
Thanks finally someone that teaches straight to the point
Thanks. I just fixed my Stihl. The pin was sticking open and after a little cleaning it's running better than it has in some time. Best of all, no mechanic bill. Also, I don't have to wait two weeks for them to get around to fixing it.
The 80 dollar an hr bill plus the two week turnaround sucks!!
Worked PERFECT. Thank you so much for the video.
Thank you for this video - you've given me confidence to give it a try!
Excellent video! I will be running through this checklist on an FS 90!
great camera angle, great audio. Very nice video. Thanks!
thanks. cleaned the carb to my Stihl chainsaw but missed cleaning out the gauze as per your video. I couldn't take the gauze out off mine but scrapped the crud out with wire and then gave it a couple of good doses of cleaner. Put the machine back together. First few pulls and I can just hear that its spluttering and wants to start. I'll try with some new fuel. Fingers crossed. Thanks again!
Thanks for teh video! I have a question .. maybe you can help... picked up a used fs130r with a zama 130B carb on it... the limiter cap had been removed .. would you happen to the factory setting for teh H and L adjust,ment?
Thank you! Your video helped me fix my hedge trimmer.
Thanks so much, the only time that I understood how it's done....perfect..
Nice! Two things inspect the tube from crankcase to carb wich runs the diaphram pump for dry rott and also rrmember to use the safety glasses that spray can shoot back at you.
Unscrew gas cap. Its pressurized
Thank you for this. Fixed my trimmer this morning using your video.
Wow a youtube video thats short and sweet right to the point. Other youtube videos waste so much time in the videos talking about random b.s. like I donnttt carreee Sharon
5 years later.... great vidya bud, no bs, straight to the point. My man!
Update: it worked!
Thank you for your clear and concise video. Your tutorial is excellent and informative. You answered all my questions and then some, Thank you again!
Very helpful video. Thank you.
Much obliged. I haven't taken it apart but was wondering if it has a pilot jet that is clogged. After seeing the screen i can garuntee that's the issue. Thanks!
Going to try this on my rs56. It's been working perfect then randomly bogged down and won't stay running. Spark arrestor was clean. It's only 2 months past warranty
Thanks for the video. Had an issue with my FC90, throttle had detached, easy to fix when you know how to get to the issue. 😊
How to de-gunk a carburetor and how to fix it. Without annoying music and unnecessary shit. that's the way I like it...simple and informative.
Helped me get my Weed Wacker going again. Thank you.
Marvelous thna you so much for this amazing tutorial!
good video i am 14 just leaning how to do this stuff so i dont have to go and pay for someone to do it and then rip me off because i am 14 and they think i dont have an idea on what i am doing you made it nice and simple so everyone could understand it thank you.
Great Stuff informative and I appreciate you sir
I just cleaned my FS91R carburetor using these instructions. Overall, it worked well. Two notes:
(1) If it's the first time doing this, the little rubber hoses are going to be a bit difficult to remove.
(2) At the 1:49 mark you show the removal of the top of the carburetor, but you don't mention there are two gaskets on the piece you remove, and a small spring under the gaskets. If someone is not careful, those can come off. That happened to me. I was able to get it all back together, but had that little spring bounced off somewhere it would have been difficult to find. So be careful on the step of removing the top after the two screws have been removed.
My screen was not anywhere near as dirty as yours. As others have noted, I'm at a loss to understand how that much debris could get to that point in the carburetor.
Awesome video! I was able to fix my weed wacker. Runs great!
Great vid. Clear and concise. Thanks.
The Zama rebuild kit for the fs90/fs100 etc. is part number RB-97.
Also I noticed you didn't remove the shield that wraps around the carb where the adjustments are made, I don't know if you removed it in the past and left it off or if for some reason yours didn't have it. It requires a T-20 torx to remove it.
On removing the two nuts that hold the filter housing-carb on my housing has plastic inserts that make it very difficult to remove the nuts so I had to use a pair of needle nose pliers in order to remove the nuts since there was not clearance for a 5/16 socket/nut runner.
If you remove the jets for cleaning the Low speed jet (longer of the two jets) is around 3/4 turn out from seated and High speed jet (shorter of the two jets) is about 1 full turn from seated as a start point, at the corners of the carb body you will see a small H or L for high and low jet positions. When I do an Ultra-sonic cleaning I use Mean Green cleaner (NOT SIMPLE GREEN) Mean Grean will not harm aluminum like simple green will at a 10:1 ratio of distilled water:Mean Green at 45c for 30 min.
Thank you for the video.
If you don't have clearance for a 5/16 socket, you are probably using a 3/8 DRIVE set. A 5/16 socket on a 1/4 DRIVE has thinner walls and there WILL be enough room.
I have cleaned my fs90 carb’ and replaced the primer bulb together with a full rebuild kit...... but, it still won’t prime, have been told it could be the “check valve” ?? Any ideas on this please ? Thanks for your time.....M..... UK...
Very helpful video and now more confident to try cleaning a carb now as was reluctant to do it incase would mess it up but it's good you also show taking it off and putting it back on
i own a fs130 and is almost identical and it did the job...very good tutorial.....keep going.
Thanks a million, your video helped me to fix my weedeater.... :)
HELPFUL , info is very well presented. Thanks!
Hi Mike,yes you are the best on you tube.Thanks
Great video👍 I have the 130r and it makes a popping sound at full throttle. Now I know why. Thanks
I enjoy this kind of videos, thanks.
Dude! Thanks so much for this.
the screen cleaned fixed mine. Thanks!
Really appreciate your videos, Straightforward, hands on and easy to follow. Question: does the fs90r trimmer have a spark arrestor screen, and if so where is it located? My machine is running a little rough and is unusually loud. Thanks.
Depends on age & country. In UK, spark arrestor has been obsolete since 2009. To find out, remove muffler & look inside-if you see mesh, it has an arrestor. Most stihls, this can be unscrewed from the muffler, but in most cases, it's a clean through(I blast a blowtorch through the muffler, followed by carb cleaner, then let dry), or replace muffler unit.
What an awsome video! Get to the point without all the bull. Thank you for making this video.
I have a sthil trimmer FS 85 pro series , I was wondering if I can use 5/32 socket on my screwdriver in order to remove the bolts from the air filter to remove the carburetor,
Great video didn't talk about how clouds for an what earth worms do when there in the ground. He talk about the problem an nothing else. Thank you very much. I will subscribe to this channel. Good bless you sir.
THANK YOU SIR , YOU JUST SAVED ME FROM HAVING TO BUY MY BOSS A NEW ONE . GREAT VID VERY EDUCATIONAL , AND MONEY SAVER JUST WISH U HAD MORE VIDS ON BLOWERS ETC . GREAT JOB THANKS AGAIN
why the fuck would you have to buy him a new one if you were using it to do his work
Hi Mike,Thanks you are the best on you tube,Thanks
Thanks, it fixed my weed eater.
Mike Miller
Great video! Can i use a air-tool to dry it off?
very clear presentation - thanks.
Good Video. Would suggest starting with idle adjustment before going to L or H adjustment.
Have an FS80 here at work, I can't imagine there's much difference other than maybe bore size. Carbs look identical. Anyway, hard to start, bogs down and cuts off after about 10 seconds WOT. Cleaned the carb, didnt take screen out but cleaned the one side of it. Still doing it Any suggestions?
Great video on how to thanks for the tip
Mike, we run these 90's, 91's and 131's, never any trouble on exaust side ??
Awesome vid man thanks for the help
Great vid!
Straight to the point. Thank you!
Thank you for this video. This is helpful.
You are good. Good voice. you stay focused and on point. You know what you are doing. The comment below said you are a legend. I think my problem is the cable come loose or broke at the carb. so you showed me what to do I'm a beekeeper and I know how to pass on info as you do I'm ( WallsBeeMan ) on you tube
Take care and thank you Tim
you think high pressure air [ from air compressor > needle point air tip] would do any damage?
I have a fs110 I figure they are nearly identical. Will try this. Mine is not allowing any fuel into the bulb, when I pump it. So either it has a hole in it and needs replacing ( again) or a line is stopped up. i hope this will fix it. Thanks for the video.
POST DISASSEMBLY: I took it apart, the screen was clean and shiny, no filth in the hole. I disassembled the priming bulb it showed no tears or holes in it, and was clean. This is a 16 year old machine, with a 3 year old carb on it, I had to have that replaced back then. The throttle cable is frayed a little, has a couple of broken wires, but the bulk of them are intact, and it works. I'll try replacing the plug in the morning when I go to town to get one. it wasn't very dirty, I put it in, late season last year, but it still might be the problem. I brightened it up, it was just discolored, not oily or wet, nor had any carbon build up , I tried to crank it then, just to see if it would, but it never even tried to turn over. So, try again tomorrow.
Any idea how to reset the idle speed screw (LA)?
Well done.
Thank you!
I put a new carb & spark plug on my Sthil Wed eater FS 55R but I can not adjust the high side so it will run OK. It will not run properly when weed eating. The idling is no problem. Any suggestions ?
Thanks, you helped me out a great deal...
I've been in the Lawn Service business for 4 years and now I can save money by doing this myself. Your video was extremely helpful. Thank you.
Awesome video 😊
hi, I have a FS 70 trimmer, can I use the same procedure for cleaning the carburetor or for this model is different?
i have a fs45c stihl ,stihl sold me a carb set ,but you need special tool to get carburettor off,what I did its a 7mm nut,i bought stanley socket set has 5,6,7,8,9 etc sockets,the 8mm socket worked really well,my issue was was'nt idling,so i used the kit,a mistake i made the side of carburettor with fuel push button i replaced diaphram but did'nt realise there is another gasket so did that and it worked.
Cool! Just try cleaning the filter! Am reluctant to disassemble because everyone else gives a doctoral thesis of all the possibilities, and it's less pain just to buy a new carb for £20 than mess around replacing diaphragm s, etc.
If all is good how many pulls should it take to start a 2-stroke (trimmer/ chainsaw/ hedgetrimmer)? Friend has just bought VERY EXPENSIVE Shindaiwa (500€!!!) And it's not the piece of cake I would have thought it should be for that price.
great explanation indeed. thanks a lot🧡💯
Thank u for ur video. Very useful.
Is this why mine won't keep running when I finally get it started?
Great video i will try on mine tomorrow
I bought a new FS91R from the dealer yesterday and it seems like its starving for gas in trimming position. If I lean the motor toward the ground it runs fine. Do you think the adjustment screw would fix that problem?
If it’s new it’s under warranty.dont fool around with it or it’s void.take it back and demand service
So good! Thanks 😊
Great help thanks
Thank you my friend!
I am pretty sure thats it....to be continued.