FS55r STIHL

guido

Well-known Member
Hello,

This trimmer is 1 year old, and boy does it have a problem! It is very hard to get started, and will barely run at full throttle. Let the throttle go, and it dies! I cleaned the carb, and checked the fuel filter and lines so far, no problem found and no change. Any of you ever had such a problem? It did lock up ones, so I took the plug off and pushed the piston down. Never did it anymore, but is sure needs more help!,

Guido.
a129395.jpg
 
Hello Jim in MA,

I forgot to add that I ran it without the muffler, and it ran a little better and it kept running at idle, although not that great. The muffler is clean,

Guido.
 
I would try replacing tank filter never had good luck tring to clean them and they aren't that expensive of a filter.You said you had muffler off, Did you check piston and cylinder walls for scoring.
 
Hello D beatty,

I took a quick look inside and it seemed fine. But the ring could be stuck on the opposite site,
I read some revues on the unit, and it is mostly bad ones. I'll need to check the EPA certs on it. If It is 50 hours, then it is probably junk! One year old and done!

Guido.
 
Yes! I have the same trimmer. 2 years ago had the same problem. Remove the carburetor there is a plate on the bottom. Under there is a fine mesh filter pushed into a hole in the bottom. This is about the size of a pencil eraser. I almost missed it since it appears like a solid bottom hole. Clean the filer mesh, and replace. I think you will be good.

Tim
 
Hello Bratta Gonia,

I looked at the port when I took the muffler off. It was clean. It is only one year old, and only premium fuel and oil has been used,

Guido
 
Hello Tims A,

I looked at the screen when I cleaned the carburetor, thinking maybe that would be the problem......not,

Guido.
 
It's likely the exaust (spark arrestor screen) or a gummed up carb. Running fuel with more than 50:1 oil mix will gum the exaust screen. I won't get into ethynol here, it will start an argument about the cr*p or what it does to fuel components.
 
Hello pat sublet,

I had the carb off, and cleaned it. Also the muffler was off, and the engine exhaust port looked clean. I'll have more time next week to look at it. For now it barely starts, and barely runs.......

Guido.
 
The 50 hr. EPA certification has nothing to do with the overall longevity of your trimmer. Check your compression. It should be 120 psi. or better and indicate if your piston/cylinder/ ring are in good condition. If the compression checks out, you most likely need a carb rebuild or replacement. A new carb is probably worth the extra money compared to a kit. I think a trip to the dealer might be worth it, if you have a good dealer that stands behind his product.
 
When you cleaned carb did you take it apart. There is a diaphragm in carb and they can get hard and not pump fuel properly.
 
Check the tightness of all the fasteners on the engine. I have seen the head screws work loose. Some take a long allen wrench to tighten.
 
And Don't forget the Fuel line!... That can drive You Nuts, it can get a Small crack and it will Suck MORE Air than Fuel, and won't Run worth a crap, if at all Larry
 
Hey Guido.

Don't know if you got your trimmer fixed but yesterday I was working on my 034 Stihl which had become harder and harder to start and in the end would not start at all.

I determined that it wasn't getting any fuel mixture to the spark plug.

I verified that fuel was reaching the pump located on the carb and after taking the pump apart I found that there were two passages blocked by sawdust residue. It looked like at least one was a vent to the outside of the pump.

I cleaned her up and the saw fired on the first pull and started on the second.

Hope this helps,

Brad
 
Hello retired farmer,

I did the easy thing, now it is time for major work,

Guido.
 
Hello motorcraftman,

They fuel lines are the new style, flexible and looked good at a first glance, will need to look much deeper I guess,

Guido.
 
Hello Brad Buchanam,

This is the worst running small gas engine that I've had the pleasure to work on.
ONE year hold, hard to start, crappy running only at full throttle and no idle. It even locked up one. It is not a commercial unit, but I had no name weed eater 20 years old run better then this thing. I'll get it going soon as I get some time.


Guido.
 
Hello,
I got a chance to work on that weed trimmer to day. It is now starting, idle is nice and adjustable. It has plenty of power, but only 1/2 throttle. Past that point will eventually die!
I cleaned the spark screen, it really did not need it. I took the carb apart again, and after blowing all the orifices, again, I started to put it back together. I noticed the needle valve actuator looked pretty high. Adjusting it brought the thing to life. I now have to see why it does not run at full throttle. I'll probably need to
just replace the fuel filter, But its only ONE YEAR HOLD! May be got into a bad batch of high test?

Guido.
 
I have either the same model or a similar one, I forget the exact model number. I've had nothing but troubles with mine. Piece of junk as far as I'm concerned. Stihl didn't win any contests with that model!
 
GUIDO,

I read the entire dialog on your problematic small engine.

I should have read here first....I spent way too much time dealing with a RYOBI weed whipper.

Carb kit...ran great for about ten minutes. Split fuel line after that, ran great for another ten. Leaky primer bulb allowing air to enter fuel line.

Something tells me that the "gas" I use is probably a root cause.

I will read deeper into these replies from now on.

D.
 
Hello dennis min,

The reason for my posting is just hat. Many replies will usually hit most problems. The one I had the exception,

Guido.
 
Go get a new carb 4140-120-0619. Make sure you have the green fuel line also. Carb is less than $30. Any Stihl dealer should have a box of them. One word problem ETHANOL
 

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