Broken (won’t start) Stihl FS55 gas trimmer diagnoses and fix

This video shows and covers the diagnoses process and the repair of a Stihl FS55 straight shaft trimmer.
I bought this FS55 knowing it “didn’t run, probably needs carb work”, among the other issue of a broken recoil (pull start) assembly.
Watch as I walk through my step by step thought process and diagnose the issues at hand.
The process is the same for almost every other gas string trimmer or brushcutter on the market!
Thanks for watching!

[@johnwarner4513]

Thanks Dave, a big help showing removing the carb, as I have a sticking throttle cable, I say sticking, its just not smooth, it tends to jump to high revs, after hitting a "high point", now I know how to get at it. Good man

[@freddiedowns2750]

Thanks for the video, it certainly helped me fix my fs55r weed eater.

[@mlatief5865]

Hi Very helpful, I will keep on top of maintenance from now on. Great vid. Thanks.

[@DavesSmallEngines]

Great to hear!

[@DavePawson]

very clear, thanks.

[@injusticiastv4644]

Good for you man saludos pelao desde Cancun México

[@winstonclarke9221]

Thanks for your answer. Davie.

[@DavesSmallEngines]

Cheers!

[@seanmcgillicuddy956]

Nice work ..

[@DavesSmallEngines]

Thanks Sean!

[@RDLR-nt4br]

Dude I would need to know how the spring engages inside the throttle of the fs55 like the one in the video. You could post a photo? the spring is Stihl Torsion Spring n.11 on the exploded view.

[@johnclarke6647]

You can take off T27 plastic screws with a drill, but you should always install them by hand with a t27 T wrench or T 27 screwdriver, otherwise you can strip out the threads. Don should have taught you that. I usually both remove and install P type screws by hand with my T27 T handle. Drills speed things up but can also strip out the torx threads in the screw./ bolt. I have mostly Pro equipment and the threads in their metal cases can get stripped out by using a drill to screw in their screws. If I use one I set it’s clutch at it minimal setting and finish torquing them down with my T handle wrench.

[@DavesSmallEngines]

Hey John - totally agree. I learned that lesson the hard way and my new videos show my change in approach to reinstalling T27’s. Thanks so much for watching!

[@davidscruggs2104]

Very good video. I think I need to buy a new carburetor and this will help. But I also may have a compression problem. Where do I go to find out what the compression for a FS 55 C should be?

[@DavesSmallEngines]

What number are you getting now David?

[@scoobydoo3477]

I worked on one off and on for over a week until I figured out the exhaust was bad, took muffler off and it run perfectly.

[@shawndubay4050]

The mufflers do carbon up especially if they are a bit heavy on oil in the mix and not ran above half throttle. Easy fix. Take the muffler off and put it carefully but securely in a vise away from anything that can easily catch fire. Take a propane or mapp gas torch to the inside and outside of the muffler and heat it until it glows orange. Let it cool off for about an hour then reinstall and it should run like new or better. The muffler is important for the engine to run properly and not cause fires. These small two cycle engines do sometimes shoot very hot sparks and can cause a grass and or forest fire. And yes these fires grow in size very quickly. That's why they also have a spark arrestor screen built into the mufflers design.

[@teddyclark2791]

Can you tell me where I can purchase bolts to attach the muffler and ones to attach the recoil unit. Thanks Ted

[@DavesSmallEngines]

Hey Teddy! Your Stihl dealer should be able to get them.

[@larryarnold1282]

Nice video…did you get a ultrasonic cleaner yet? Didn’t see a video in your line up

[@DavesSmallEngines]

Yes I have one! Works great.

[@johnlasher1568]

Dave, great video on replacing carburetor. I purchased a carb kit and replaced everything. It will start and rev but only stays running for a few seconds. Thoughts?

[@DavesSmallEngines]

Hey John - check the gasket between the carb and the block. Make sure it has the holes and they are lined up.

[@johnlasher1568]

@@DavesSmallEngines Thanks for the tip. It is now running longer but not perfect. Assume now I need to watch your video on adjusting carburetor?

[@DavesSmallEngines]

@@johnlasher1568 I think so. Tart at 1.25 turns out for both the L and H

[@brandonfeland4723]

Set your H, once set, let go of throttle. If it stalls idling, adjust the idle screw (bottom of the 3), until it starts and runs on idle. Then at this point, you would adjust the L screw, once set, (only if the head is still spinning at this point) go back to the idle screw, and adjust until the clutch just disengages (stopping the rotation of the head on idle). (keeping in mind, directions here were used after already messing with all the settings, and trying to figure it out for myself.. Lol)

[@nikolavincek2347]

for starter spring you need to heat to red hot and then bend if not want to brake again

[@DavesSmallEngines]

Good tip! I'll try that.

[@timrussell1559]

Why pull the plug and spray fuel down into the cylinder? Why not just simply and quickly shoot a little gas directly into the throat of the carb? It accomplishes the exact same thing and takes a fraction of the time and effort to do. Spraying fuel into the carburetor will also quickly determine if the crankcase is building enough pressure on the downstroke of the piston to allow fuel to enter the cylinder through the intake port

[@MolotovWithLux]

Change oil-gas constituent mixture

[@steverollins7904]

Hey Dave, I know this is a older video but I have a FS 55 that will not start. I have spark but when I put a little fuel in the spark plug opening it still won’t start. Any ideas? Thanks

[@DavesSmallEngines]

Do you have compression?

[@steverollins7904]

@@DavesSmallEngines Just put a compression gauge on and I pulled 10 times and have 110-115 pounds . In the beginning I did have a completely clogged spark arrester but cleaned that up real good. Any help would be so appreciated .

[@shannongrim7212]

I have a fs55 would like help turning it

[@DavesSmallEngines]

What are you struggling with?

[@9-thanhhuyen-648]

Có bán máy đầu máy cưa sting 010 còn tôt không ban

[@douglasweese923]

Dave, my FS55 stilh will start or idle but when I try to throttle up it has no power. I checked the spare arrester and it’s good. Thought?

[@DavesSmallEngines]

Can you take a video and upload it? I may be able to help.

[@tysonmclane5909]

Wish i could figure out what is wrong with my FS110 It starts but it wont throttle up. It had a bad primer bulb which i replaced and was working previously to the crack in the primer bulb.

[@DavesSmallEngines]

Hey Tyson - did you take the purging side of the carb off?

[@tysonmclane5909]

@@DavesSmallEngines I just took the top bit off, it was running rough and having trouble spooling right before but that was when i noticed the cracked bulb.

[@DavesSmallEngines]

@@tysonmclane5909 how are the carb diaphragms? Check out a few of my videos if they look brittle it’s time to replace. I have a few examples in my videos.

[@shawndubay4050]

One thing to know about all the Stihl 4mix engines including the 110 is that they have a plastic camshaft and cam gear. They do get hot and will wear down. If you fix the fuel delivery issue and it still will not throttle up my bet would be the camshaft is worn down and needs replaced.

[@winstonclarke9221]

Would that carburetor work on an fs 85.

[@DavesSmallEngines]

Yep!

[@petebergen6178]

Why don't you clean that thing before you work on it ?

[@jameslovering9158]

Why not clean the unit first before stripping down ?

[@DavesSmallEngines]

I should have, for sure!

[@juliodiaz368]

I got couple question

[@juliodiaz368]

I have FS 55 Stihl weed eater won't start I put the new carburetor but still won't start

[@DavesSmallEngines]

What have you tried?

[@halcampbell1384]

Dave, It really bothers me when during a repair little to no effort is made to clean debris from the unit. Ok I understand it may not be necessary during a diagnosis or tear down, but after that? Come on man, you know better than that!

[@DavesSmallEngines]

Hey Hal! You’re absolutely right. I made this video at the start of my recordings - I have learned a lot since then. Thanks for watching hope to see more comments from you in the future!

[@juliodiaz368]

Hi

[@DavesSmallEngines]

Hi!

[@Sassenhaim]

Handtools any one 🤭I don't even dare and use a power tool whilst fixing a trimmer 🤣 The chef won't let me 🤫 But he's right though, a lot of screws broke off because of that The fuel issue was bad fuel, a 2 stroke needs oil and this is what pure unleaded fuel does to diaphragms and running it for a while and then put it away for a long time 😘🤣. The "rubber" is kept rubbery because of the oil.

[@DavesSmallEngines]

Cool! Great to know!

[@jasoncarden9200]

they last up 5 years

[@eathans_small_engines8665]

I find the recoils arnt the best on them

[@othmanshah9949]

....

[@DavesSmallEngines]

?

[@istvanonodi4723]

Magyar nyelven

[@DavesSmallEngines]

👍🏻

[@jasoncarden9200]

sorry men neew new stihl new it look you removing the carb a new stihl my 70 and 91 are new

[@jasoncarden9200]

look old too