I have a Stihl Pro FS85 weedeater that has been running fine for years. Now I can't get it to run over an idle. It chokes down when I pull the throttle. I changed the spark plug and attempted to adjust the carb. The carb adjustments do not match what the manual show. The manual shows three adjustment screws but the carb only has one! what's up with this? I have searched online and cannot find anything concerning this. Anyone have an idea?
Not all trimmers of the same model have the exact same carbs on them. It sounds to me like you may have a blocked spark arrestor screen in the exhaust.
Thanks for the info. How do you find out what carburetor it is? How do I get to the spark arrestor screen?
You can get to the spark arrestor by removing the muffler..Carb spray cleaner a tooth brush works well for cleaning these... I'm afraid you'll have to remove the carb to find out exactly what you have... If a Walbro,, Zama,, etc, go to there websites download the service manual... Buy a carb kit recondition the carb if everything else is well,, You'll be good to go!!!
That is a great brand of trimmer. Probably one of the best. I think Cheese has it right. Clean that spark arrestor and replace or clean the plug and your probably good to go for a year. I do it once a year now that I have found how much better it makes them run.
Here is what I do. I pull the muffler and clean the screen with a brass wire brush. I then clean the muffler engine port of carbon with a small stick of wood,that way I wont damage the cylinder or piston. Wooden popsicle sticks work great for cleaning the port.
Thanks, I have been reading some other information on the net that people are removing the screen completely. Is this ok to do? Also, I have adjusted on the one adjustment screw and now I don't know how it should be set initially. do I need to completley remove the muffler to clean it?
please forgive me for asking about removing the muffler, you have already said to remove it. another senior moment!
I got it fixed! I took the muffler off and cleaned it and took the carb apart and cleaned it, put it back together and it it fired up and ran like new. Thank all of you for your help. This is a great forum.Beer 4U2
Bruce
Great! Glad you got it! Thanks for the update.
Might want to use high test gas from now on.
I don't recommend it. Use non-ethanol fuel if you can.
Tags: stihl, fs85, weedeater, adjustment, spark arrestor, arrestor screen, muffler clean, removing muffler, spark arrestor screen