# stihl fs 80 no start ?



## springer57

hi everyone, have a stihl weedeater that has always been a little hard starting. Worked fine last weekend, now just wont start, has new plug,120 on the compression, definitelly getting spark just wont fire. even tried a little starter fluid straight into the carb and nothing. I am a mechanic (AUTO ) but I am stumped any ideas anyone ?? was always a good machine just 
cany figure it out thanks !!


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## tommyj3

Remove the arrester screen in the muffler and clean it.


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## springer57

thanks tommy for the reply , allready tried that, I cleaned the muffler with carb cleaner I am sure its clear. Been searching on the forum for some similar problems and found replies saying the flywheel key could be sheared thus throwing it out of time ,just checked it and its okay.Just how do you check the compression ? With a guage like the one used on an auto engine? I am an auto mech. and used the guage I use on cars Im beginning to think it may not have the compreession I think I have.Is there something different on this small engine? procedure wise I mean ??? thanks


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## tommyj3

You use the same compression gauge as auto, screw in plug hole and pull engine through 3 or 4 times, should have around 130-150 psi.

I know you said you put a new plug in engine, but I have seen bad plugs even when new.

Plug: Champion RCJ6Y or NGK BRMR 7 A
Gap: .020 in or 0.5mm


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## springer57

pulled the plug and grounded it to the cylinder/ jug and it has a good spark even tried a second plug.what is the " bottom seal" I have been reading about , its purpose,and would I have compression if it were bad ???


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## tommyj3

If a bottom seal is bad (crankshaft seals) the compression will still be good. Make sure the carburetor screws are tight and the gasket between carburetor and cylinder is not causing a leaking air.


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## springer57

hey . Stopped by the stihl dealer on my lunch hour today had their tech take a look. He seems to think the coil is bad and doesn"t have a hot enough spark to fire the plug when the plug is installed due to the cylinder pressure . I never ran into anything like this on a car ? does it sound logical ?? thanks tommy


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## springer57

Hey everyone . I tried to buy ignition for it and new stuff is no longer available, so I found a dealer with some used ones he took in as "trades". bought a used ignition and it starts first pull consistently. That thing had to be going bad for some time. thanks again :wave:


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## Rentahusband

Glad to hear.
Dean


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