Stihl FS110R Trimmer will not run.

MrDave

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Sep 9, 2017
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Hi All,
Hopefully someone can help. My Stihl FS110R trimmer was hard starting mid July. Finally got it running after 10 min. Last week I had same issue.. sputters very slightly but won’t start. I have since replaced the fuel and air filters. Spark plug.. swapped for a new carburetor. I adjusted the valves with the Stihl kit. Installed new fuel lines. Checked the timing the key and shaft look perfect. I’m getting a blue spark on the plug. I took the muffler off and fully cleaned.. spark arrestor was clean. I tried starting with no muffler.. same. I added new fresh fuel/oil mixture. I poured a cap full in the plug opening and still will not fire. Plug seems to be wet when I pull it. I tested the kill switch it is ok. It feels like good compression when pulling. I cannot think of anything else to try.. nothing has changed.. it sounds like it sputter but never runs. Looking thru the muffler port the piston looks clean. My one thought is even though a blue spark on plug could the ignition module still spark the plug but not enough to run?
Thanks, Dave
 

blueberrymuzik

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Dave, my first thought is that with a cap full of fuel poured in the plug opening, it is probably severely flooded. Here is what I would recommend- remove the plug and turn the trimmer over so that any excess fuel in the cylinder will drain out. Then take an air hose and blow gun and blow compressed air into the cylinder through the plug hole for about 1 minute. after that either use a different plug or use the compressed air to dry the tip of the plug. You can then try to start the engine first without using the choke. If it does try to start after about 5 pulls, try the choke for 3 pulls, then try 5 more with the choke off. If it hasn't started or attempted to start, remove the plug and add about 5-6 drops of fuel, then reinstall the plug. It should at least fire. Please let us know your results.
 

bertsmobile1

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because of the tiny engine volume 31cc these 4 mix engines with decompressors are unbelievably sensitive to valve lash setting, 0,001" out and they won't run.
Further more you have to grind a regular feeler to get it in there or buy the really expensive Stihl service tool.
I have a lot of BR400 & BR 600's in the run and they have been a bugger t keep in tune.
Double ditto on the previous advice as well.
Try warming up a plug till you can just barely hold it in your hands before you put it in and only a drop or two of fuel to start it.
 

EngineMan

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Put a meter on the ignition module and check it..!
 

bertsmobile1

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All you can check with a meter on a self triggering magneto coil is the secondary windings.
I am yet to find one where the windings are the problem. It is always the trigger chip and once the Atom patient ran out everyone has been embedding the chip so they are not servicable.
 
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