Need help with Stihl FS45 trimmer (weedeater)

[coppermouse]

It was running fine earlier this year, now it starts then dies
I put new gas in it.
Any help is appreciated

 

[xscorex]

pull the spark plug out, clean it, put it back in. then try replacing the air filter. then if that doesnt work you might want to try adjusting your carb if you can. If that fails take it to a repair shop.

 

[george2c]

check your fuel filter, todays gas is junk. take the filter off and try blowing threw it. If you cant blow threw it or only a little air then put a new one in. most get partially gunked up and run and shut off.

 

[Bender78]

I had a similar problem with my Stihl chainsaw last year. I tried everything and finally gave up and took it to the dealer. Turned out to be the fuel line softened by the junk gas; it would close off under suction from the carb. The guy there told me that it happens a lot these days.

 

[dan76]

x2 on the above.....plus

Oftimes during even short periods of storage with fuel in the tank/carb, fuel may evaporate leaving deposits clogging the carb passages. Get a spray can of carb cleaner, remove the fuel line and spray the interior of the fuel tank. Let the cleaner flow through the line watching for debris. Next remove the air filter and spray into the carb throat. Pull the engine through a couple of times and then try to start it. You may have to run the throttle at 1/2 open during the starting attempt. If this does not work and you feel competent, remove and clean the fuel bowl. If you see deposits, then spray carb passages and replace the bowl and try to start.

I've used WD-40 as a starting fluid sprayed onto the air filter. If the carb is clogged, WD-40 gets the engine running for a few moments allowing fresh fuel to be pulled through the carb passages, clearing them of deposits.

 

[Freejack]

First, before you do anything else, check the spark arrester, it's a fine screen that covers the outlet of the muffler and regularly gets clogged with carbon, especially if you are on and off the trigger alot. If you are in an area that does warrent or require a spark arrester, simply remove it.

I worked in a Stihl service shop in college and 50% of the time when a customer came in with a trimmer wasn't running or would not speed up, simply removing the screen that serves as the arrestor and it would be running great again.

Jake

 

[usa89gt]

I had the same problem with my Stihl and after 4-5 uses the carb was "varnished" and had to be cleaned. There is also a small screen near the exhaust that apparently gets clogged up that should be removed. I haven't done this yet but will explore it.

 

[coppermouse]

Is the spark arrestor visible from the outside of the muffler?
I don't see any screen, just a small outlet

 

[Bfoughty]

I'd have to go with fuel line first. I would check the spark arrestor in the muffler outlet also.

 

[semi42]

other things to check....

make sure the tank cap is on tight, no leaks and that the vent valve is working

 

[ossaguy]

Starting and dying it almost always fuel/carb related.If the fuel filter & line are ok,take off the carb and take off the 4 screws for the main diaphram cover.More than likely you will fnd that the old fuel has hardened up the main diaphram.If it's not all gummed up inside, or corroded,a gasket/diaphram kit may be all it needs.

If not,a new carb may be needed.If it's a Walbro carb,it will usually be way less money getting it from a Walbro dealer,vs. getting the same carb from Stihl.Sometimes it's like half the cost.Just something to consider. The numbers will be stamped on the alumium carb body.

To prevent it from reoccuring,use the "Marine-grade" Sta-bil with the fuel,or at least the better oils that now that have the stabilizer already in it.Gas is considered stale after 30 days,at least in this part of the country.

Over half of the repairs in the shop are all fuel related lately.It's getting worse.

I hope you get it fixed.

Steve

 

[Indy_500]

THe carbs in weed eaters get varnished up pretty good from getting the mixed gas ran thru it, clean those carbs!

 

[coppermouse]

Ok I took apart the carb, cleaned it and rebuilt it with a rebuild kit from the stihl dealer.
Now it is running really rich and the only way I can keep it running is to lean it completely and or take off the air filter. Any idea what I can do to remedy this?

 

[Random Guy]

x2 on the above.....plus

Oftimes during even short periods of storage with fuel in the tank/carb, fuel may evaporate leaving deposits clogging the carb passages. Get a spray can of carb cleaner, remove the fuel line and spray the interior of the fuel tank. Let the cleaner flow through the line watching for debris. Next remove the air filter and spray into the carb throat. Pull the engine through a couple of times and then try to start it. You may have to run the throttle at 1/2 open during the starting attempt. If this does not work and you feel competent, remove and clean the fuel bowl. If you see deposits, then spray carb passages and replace the bowl and try to start.

I've used WD-40 as a starting fluid sprayed onto the air filter. If the carb is clogged, WD-40 gets the engine running for a few moments allowing fresh fuel to be pulled through the carb passages, clearing them of deposits.

String trimmers use diaphragm carbs. They don't have fuel bowls, although that is good advice for engines that do.

 

[coppermouse]

Well I took it all apart and completely cleaned it inside with carb cleaner and replaced all the pieces in the rebuild kit and it is now running super rich. I had to turn the low idle and high idle mixture screws all the way in just to get it to run and took out the airflter just to get it to run. It seems like a little spray of fuel comes out of the carb air intake with the fuel filter off. Help please

 

[Charles (in GA)]

Is the priming bulb OK? Perfectly OK. The reason I ask, is my Sthil pole saw had trouble starting and running, and eventually the primer bulb broke loose at the retainer ring. But I was having trouble before that and did not realize it. Got some sorry excuse from the part man when I bought a new piece of plastic that "the oil companies have changed the gasoline and it damages the bulbs" and claimed the new ones were different. Yea, right, and no one else is having trouble with the same gasoline? I've been totally turned off by this Sthil product and have vowed to never again buy a Sthil product, its been lots of little issues since the beginning.

Charles

 

[coppermouse]

Yeah the primer bulb is good I checked that.

 

[57210]

I just got through replacing the fuel line on mine. The new gas is pretty hard on them.

 

[coppermouse]

I checked the fuel line, that was the first thing before rebuilding, it is OK. The problem now is that it is way too rich and the only way to get it to run is tuen both mixture screws fully lean and take of the air filter. I also removed the spark arrestor

 

[robin64]

Hi -check that their is no pinhole leak in the fuel line or primer bulb Replacing both is cheap but both can be causes of the symptoms you describe however sometimes an air leak in either is difficult to detect but it is a common problem

 

[DynoDave]

Sorry to hear about this coppermouse. I have an FS46, and EVERY spring, regardless of winterizing method, I pull the lug and clean it, and the air filter too, but this is never enough to get it going. I ALWAYS have to give the inside of the carb a good douching with carb cleaner, pour the cleaner back out of the carb/plug hole, and and leave the plug out until things dry. Then, and only then, will it start and purr like a kitten. It's been this way since year one, and works every time. I'm sure it's not the "recommended" method, but I go with what works!

I've had great luck with this Stihl unit. I'll never again go cheap on a string trimmer.

I hope you're able to get yours up and running well.

FYI...I looked this up the other day, while trying to recall my oil mix ratio. There are a couple of carb mixture setting directions.

http://www.stihlusa.com/WebContent/CMSFileLibrary/instructionmanuals/FS-45-46-Weed-Trimmer-Instruction-Manual.pdf

 

[DHS]

You can adjust the needle valve by bending the lever. It should be under the cover with 4 screws holding it on. It could be flooding because the needle valve is not closing.

 

[Charles (in GA)]

Wow! three year old thread up from the dead, first post for a new member.

Charles

 

[DHS]

Haha, I guess I need to look at that before I post.

 

[MarkG]

Wow! three year old thread up from the dead, first post for a new member.

Charles

Now you have ME doing it!

But I have to chime in---I hate this trimmer! Mine has never run well and now that I'm trying to remove the carb to clean it, even THAT is a problem because Stihl has molded the plastic cleaner cover in such a way that there is not enough room to even fit the correctly-sized socket in there to remove it!

Do NOT buy from Stihl unless you are ready to do a LOT of fiddling to be able to work on your equipment (which you WILL need to do!).

I'm stuck with this piece of junk, so I ordered the carb re-build kit and will put it up for sale ASAP (if I can ever get it running again) I lost confidence in 'quality brand names' after my experience with this dog of a machine. My 25 year-old corded Weedeater runs circles around this thing, even when it WAS running.......

 

[JerryB]

I have a somewhat different experience with Stihl trimmers:

My neighbor & I have used Sthil trimmers for years. They work better and are more reliable than any other trimmer we have tried. Our machines are used for everything from maintenance of our private properties to fence line maintenance around our airport and mutual water company properties. We even entrust these machines to be used by the occasional (well trained) hired hand.

Recently we were having a starting problem with the larger machine. Checked and cleaned the air, electrical and fuel systems with little improvement. Finally took it to our local dealer who looked at it and said the carburetor needed replacement. He said they have had bad luck with rebuilding the carb, and recommend replacement. This was done overnight, and machine now starts and runs great.

Although we are both experienced mechanics, we really believe it is just easier to take these specialized machines to a specialist shop. On the few times I have had a problem I couldn't solve, the dealer would look at it at the counter, tell me what is wrong, then adjust or replace the offending part while I watched. Can't beat that!

 

[MarkG]

UPDATE: Ordered new carb, air and fuel filters and spark plug. Once I get these and install them and re-fill with fresh gas/oil, we'll see what happens.

 

[MarkG]

Is the priming bulb OK? Perfectly OK. The reason I ask, is my Sthil pole saw had trouble starting and running, and eventually the primer bulb broke loose at the retainer ring. But I was having trouble before that and did not realize it. Got some sorry excuse from the part man when I bought a new piece of plastic that "the oil companies have changed the gasoline and it damages the bulbs" and claimed the new ones were different. Yea, right, and no one else is having trouble with the same gasoline? I've been totally turned off by this Sthil product and have vowed to never again buy a Sthil product, its been lots of little issues since the beginning.

Charles

Likewise! Sounds very similar to my experience. Currently waiting for more replacement carb parts from China, so I'll be without this trimmer for most of the mowing season. I'll be looking for another trimmer, but it will not be a Stihl!

I've sprayed everything (the original, like-new carb) thoroughly with Gumout, washed out the fuel tank and put in fresh gas/oil mix, used starting fluid, and still nothing. Either Stihl is the most over-hyped, over-priced, crappy equipment name out there, or I got a total lemon!! Wish I would have returned immediately instead of thinking it could be fixed. I'm done with anything 'Stihl'. If you're looking for any power equipment-----you've been warned!

 

[Karen62]

I too am disappointed and frustrated with the STIHL fs 45. It has never run well. I am cleaning the carburetor and the exhaust screen. I am trying to replace the fuel filter. The fuel line is not long enough to fish it out of the gas tank and now I have accidentally pulled the filter off the line. How do you loosen the gas line into the tank enough to replace a new fuel filter?

 

[thammel]

Go on Amazon and buy a new carb. They are cheap and it will likely solve your problems.

Tom

 

[jonascap]

Fix it, sell it, buy an electric. I had the FS45 and year after year trouble. I finally had a carb replaced professionally and when it was running good sold it. I bought a Makita 36 volt and couldn't be happier. It uses the batteries from my tools, I have a 2.5 acre yard and rarely do I need to use a second set of batteries if I stay on top of trimming. It's super quiet and requires very very little maintenance. It's way easier to use, easier to start, no fuel mixture work, no winterizing, no fuss, no pull starting, no fumes, no hearing protection, no spring headaches. I pretty much use an electric solution now in place of a gas wherever there is a reasonable solution in the market.

Go electric, you won't regret it!

 

[Voi]

I bought a Makita 36 volt and couldn't be happier.

XRU07Z or XRU09Z?

 

[bighead51]

is the inlet needle set at the proper height? Are you sure the diaphragm and gaskets are installed in the proper order? These little carbs. are not easy to rebuild correctly unless you have done several.

 

[rburke65]

Wow....what happened to the quality of Stihl products?

 

[DFB]

I just rebuilt an old FS45 before that wouldn't stay running and would keep flooding. Took it apart and cleaned it up numerous times

So got a carb pkg off Amazon a complete assembled carb, gaskets for both sides, two xtra primer bulbs, a new dual tank hose, and two gas filters all for $17.

Not even worth the time to take it all apart and to clean and reassemble it anymore.

10 minutes after the kit it came in I was back up and running.



Oh I forgot to mention...also came with a new sparkplug and air filter too!

 

[bighead51]

Stihl Quality? A carb. on any piece of equipment is only as good as the Fuel you run thru it !

 

[DJL1967]

First, before you do anything else, check the spark arrester, it's a fine screen that covers the outlet of the muffler and regularly gets clogged with carbon, especially if you are on and off the trigger alot. If you are in an area that does warrent or require a spark arrester, simply remove it.

I worked in a Stihl service shop in college and 50% of the time when a customer came in with a trimmer wasn't running or would not speed up, simply removing the screen that serves as the arrestor and it would be running great again.

Jake

Yes that is what happened with my Stihl 45 and after I cleaned the carbon off the screen it worked just fine.

 

[jonascap]

Xru07z

 

[Firebrick43]

Wow....what happened to the quality of Stihl products?

Well it's really still there. However the DIY consumers are demand cheaper products and stihl, right or wrong, is giving them some cheaper products. The fs45/46 are "occasional use machines". They are maybe somewhat better than big box string trimmers but they are not stihl a traditional pro models. For 50 or 60 dollars more you could have had a pro model fs70r and for a 100 a very awesome (performed flawlessly now for 8 years) fs90r 4 mix.

For you average sub 2 acre homeowner a battery powered Milwaukee/makita/dewalt is really going to be a better choice. Hell for years I used an European scythe on my 10 acres (I hate 2 stroke trimmers) and didn't buy the fs90r until I was mower 2 other family members lawns due to their health. If you keep it sharp it works really well with no noise.

 

[thertel]

I'll second the fs90r, that thing is a beast, Mine is on year 5 still going strong on my acre. Never winterized, don't drain it at the end of the season (i'm not really sure the season ends here...), I just use ethanol free fuel from the local race track with the needed mix in. It really seems to prevent all the carb issues I hear about with power equipment.