Stihl FS 38 trimmer mystery!!!!!!!!!!

goosemasterkl

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I'm working on a Stihl FS 38 trimmer that a friend said he couldn't get it started. I checked the compression and it had 90#. I then checked the spark and it was kinda eratic so I put a new coil and flywheel on it Finally getting a spark but still won't start. I then put on a new cylinder with new piston and rings now it has 120# of compression. But still won't start; doesn't even try to hit. I then put on a new carburetor; still nothing. It has kinda of backfired out the carburetor a couple times but that is as close as it gets to even making a sound of starting. It won't even hit using starting fluid. I'm stumped; I put everything on it new that I can think of. Somebody give me some ideas please. Thanks in advance to anyone who responds
 

Fish

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Check and make sure that the new flywheel's key is not sheared. It is easy to not torque the clutch back on sufficiently.

If the key was fine, put back on the old flywheel and coil. There are a few versions, and that may be an issue.
 

goosemasterkl

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I'll change out the flywheel and coil and see what that does. Could the oil seals be sucking air ;enough to make it not hit?
 

Fish

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Yeah put on the old coil and flywheel, the new style coil requires a new crankshaft too.

fs38crank.PNG
 

goosemasterkl

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Isn't there anyone out there can give me a fix on this FS-38 trimmer? I've tried everything to no avail. Thanks
 

Scrubcadet10

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did you look at the flywheel key like fish said?
 

slomo

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Isn't there anyone out there can give me a fix on this FS-38 trimmer? I've tried everything to no avail. Thanks
He put a new engine on this thing. Doens't need a key LOL.

slomo
 

StarTech

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You did check the spark arrester?
 

HarmonySeeker

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These are the times when one might consider an nice 80 volt electric weedwhacker. They do a great job, no more oil and/or gas, and a refill is as close as the next battery.
I'm not there yet, but I'm getting close.
 

StarTech

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But just how does the batteries recharge and how many do needed during the cutting 3000' ft fence line 4'-10' on each side? I usually go through 1 to 2 gallons fuel mix per cutting along multiple refills of trimmer line.
 
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