Stihl trimmer FS55

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  #1  
Old 09-23-03, 11:26 AM
951Tom
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Stihl trimmer FS55

I found a new stihl trimmer in a trash can with a bent shaft. So I removed the shaft and started the engine. It started up on the second pull. The problem is if I quickly open the throttle all the way, it bogs down and stalls. If I gradually open the throttle it will rev up like a scolded dog. Does it need a load on it to run properly? I'm awaiting on a new shaft to be delivered.

Thanks!
 
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  #2  
Old 09-23-03, 06:05 PM
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Sounds like the carburetor needs to be cleaned. Other things that are good to do on old trimmers in make sure the fuel lines aren't cracked and make sure the muffler isn't clogged with carbon.
 
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Old 09-23-03, 06:55 PM
951Tom
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Is the FS55 an old model? I could not find one speck of dirt on it. It looks brand new, not a scratch. When I took the engine covers off...still spotless. There is one screw on the carb. Is this the mixture screw? Thanks for the help.

Tom
 
  #4  
Old 09-24-03, 12:31 AM
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Hello Tom!

Sounds like a good find! I'm not sure how many years they have made that model trimmer, but it sounds like you made a good find! Try backing that screw you see out about 1/4 turn or so. You may need to clean the carb, but backing that screw out a bit might just do the trick. A load will also make quite a difference, and I wouldn't run it too much at full throttle without the shaft and head.
 
  #5  
Old 09-25-03, 07:56 AM
951Tom
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Thanks Cheese. Is the screw for mixture or idle speed? I took the carb apart and cleaned it but now the primer button doesn't fill up all the way with fuel & it still won't accept any throttle. i don't see any cracks in the fuel hoses. I'm starting to realize why I found it in a trash can.
 
  #6  
Old 09-25-03, 09:40 PM
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Sounds like a mixture screw. If the primer does not pump fuel, check to be sure the fuel lines are connected properly. The port that blows out from the primer should connect to the line going to the tank, with nothing on the end. The other line should have the filter on the end in the tank. Make sure the fuel lines don't have a crack or pinhole.
 
  #7  
Old 09-26-03, 05:13 PM
Fisher
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Look real close at the fuel line, and you will see many cracks
and holes, as Stihl knows about the problem and should fix
the problem for free, as well as go through the carb.
Every one of these fuel lines has FAILED, and the new replacement should be a green color. But the repair should
be covered, if not, let me know, and I will confront Stihl at the
EXPO next month.
Fish
 
  #8  
Old 09-26-03, 11:49 PM
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Ahhh...THOSE fuel lines, lol. Yep...they are the accordian-looking ribbed lines right? If so, that would definitely be a good place to look for the problem.
 
  #9  
Old 09-27-03, 12:16 PM
951Tom
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Just got done playing with it some more & now it won't rev up at all but it will start cold on 2-3 pulls & idle for a little bit. I took the carb off again and cleaned the jets but it made no difference. It fills up the primer bulb half way, but not all the way like my Poulan leaf blower does. It still has the black ribbed hose and a smooth hose all in one assembly that seals to the gas tank. I pressurized the fuel hoses and they're air tight. Plus I examined them under a magnifying lens and didn't see any cracks. Should I replace it anyways? The fuel filter isn't dirty, the screen was still white. What should I try next? Could the crankcase seals be leaking? Anyone have any parts for this for sale?

I'd love to get this running now cuz today my trusty old Weedeater from 1983 was screaming as usual and then all of a sudden won't hold high revs. Thanks.
 
  #10  
Old 09-28-03, 12:00 AM
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You may need to rebuild the carb. The diaphragm in it may be distorted or hardened. Did you remove the tiny screen in the carb and clean it out well?
 
  #11  
Old 09-28-03, 08:27 AM
951Tom
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yup...I cleaned out that screen & poked all the holes out with thin twisty wire and air afterwards from my compressor. Will a Stihl dealer just give me the new green fuel line? Since I'm not the original purchaser, does the fuel line warranty still apply? I'm gonna try a carb rebuild kit but I didn't see any tears on the pump diaphram & everything looks good/new. Which way does the diapram go? Does the metal circle face the carb or the cover? If you need to see pics of anything let me know. I can post them on my server. I did find one thing strange, a small rubber disc(2-3mm diameter) was stuck on top of the main carb jet...I removed this but it didn't make a difference. I really appreciate you helping me.
 
  #12  
Old 09-28-03, 11:28 PM
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The metal circle with holes around it on the diaphragm goes toward the carb...towards the tab.
 
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