Stihl fs85 trimmer


Old 06-02-07, 06:59 PM
Thread Starter
Join Date: Apr 2006
Posts: 34
Stihl fs85 trimmer

I have a stihl fs85 string trimmer that will not start. Fuel lines are new, new fuel filter. New park plug. Carb is clean. Fresh gas/mix.
Good compression, piston looks good, spark arrestor/muffler clean.

I have spark at the plug - seems to be ok? plug gapped at .20"
Can't even get it to "pop"

After 4-5 pulls of the starter, removed the plug, and it is wet, almost like it is flooded. Tried starting it with no choke, same thing. Tried starting it with "no throttle", same thing.

Anyone had this issue? Suggestions?
Also, what is the air gap supposed to be set at on the flywheel??

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Old 06-02-07, 08:23 PM
Join Date: Jun 2006
Location: St. Louis
Posts: 2,365
Sounds like you have fuel in the crankcase, liquid, not vapor. I would suggest removing the sparkplug, place a paper towel over the hole and give it a pull, if it's wet, keep cranking until it is dry. Have a good one. Geo
Old 06-03-07, 05:06 PM
Thread Starter
Join Date: Apr 2006
Posts: 34
Unhappy still nothing...

Tried this - cyl. doesn't seem to be full of fuel. Even sprayed carb cleaner in the cyl. to clean/dry it out. Then, used compressed air to completely dry things out...Still no fire. After only 3 pulls, plug wet again.

Wondering if spark is weak??
How do I go about checking for weak spark?
What is the air gap supposed to be set at??
Old 06-04-07, 11:00 PM
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Join Date: Jul 2001
Location: USA
Posts: 16,818
Plug should be set closer to .030". Check again for spark. If the spark is a crisp snap of blue, then it's good. If it's a thin orange spark, it's weak.

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