OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Trimmers and Brushcutters Two Stroke Trimmers & Brushcutters Stihl FS36 line trimmer

Hi all, picked up this trimmer today and was wanting to know if anyone can help out with the initial carb settings. Someone has played with the mixture settings and they are out by a mile, so i cant get it to run long enough to make any adjustments.

Here is the owner manual:
http://www.stihlusa.com/WebContent/CMSFileLibrary/instructionmanuals/FS36_Manual.pdf
bigted, as I read the manual, the mixture screws have very little effect.

See this instruction file:
http://www.ehow.com/how_7537113_adjust-fs36-stihl-weed-eater.html
Like the owner manual, they expect it to start and run with the screws anywhere from right in to right out. If the machine won't start, and you have spark and compression, it seems likely you'll have to go through the procedure for diagnosis: try a spoonful of fuel in the spark plug hole, and if it starts and runs briefly, you know the carburetor is not delivering enough fuel (or it needs choke). If it continues to run, fiddle with the choke until it warms up, then try to adjust the mixture while it's running. If it runs and stops when primed that way, even with choke, you have to go through the procedure: check the fuel pickup, check the primer, strip the carburetor, replace diaphragms if necessary, and clean it. I haven't been able to find a free service manual for the FS36, but if you post the carburetor make and model we can probably find the manual for that.

Thanks Grumpy, i got it running today after stripping and cleaning the carb. Diaphragms were in good shape so i reused them. Yes, youre right, it starts best when both screws are right in although still wont take full throttle. Once you try to load it up it dies although idle is sweet. Playing with the mixture screws has little effect. Tomorrow i'll change the pickup filter and remove the mesh filter in the carb and see if that helps.The carby is a mexican made Walbro but i cant remember the part no. on it now from memory, but i'll note it down tomorrow when i pull it off again. Oh, and thanks for the links, the owners manual in particular is very handy.

Ok, so it still runs like a dog and cuts out after a few seconds. The carb is a WT 160b. The problem it has is that the primer does not fill up when you prime it. The primer works, a new one did the same thing, there is fuel flow when you disconnect the fuel line to the carb, the filter is new and there are no leaks in the line or grommets around the carb. The problem appears to be internal, fuel is not getting through the needle and seat, when i place a small wire through the breather hole on the underside of the diaphragm and gently press down it opens up the needle and lets fuel go through and ultimately fill the primer bulb. So my question is this. What is preventing it from opening? Do i need to tweak the lever that the needle clips onto in order to adjust the flow?, or could there be something else stopping the flow.

bigted,

Try removing the fuel filter in the carby and see if it runs ok. If so replace the fuel filter don't even try to clean it.

bigted, following Bruce's advice, I suggest you start with items 54 and, especially, 55 on the Illustrated Parts List in the WT manual here:
http://www.walbro.com/media/21907/WTseries.pdf

If that does not fix the problem, it will be time to set the metering lever height, inspect the needle, etc. and go through the process as detailed in the manual. Please keep us posted as you go - hopefully we can help if you get stuck. And be careful when you remove the metering lever - last time I did one the little spring pinged into the distance and it took me 20 minutes to find it.

Thanks Bruce. I removed the filter in the carby as per our phone conversation, so it's not the filter. So that leaves me with Grumpys recommendation to to play with the metering. Needle, seat etc have all been inspected when i had the carb stripped down a few days ago, they're all good. My guess is i bent the metering lever when i was re-installing it into the carb body. As for the spring Grumpy, the first time i pulled one apart the spring went flying and after a lot of cursing and searching still couldn't find it. I'll post the progress to keep everyone up to date and thanks for the link.

also pay to see if the spark arrestor is clean my uncles one was playing up had 4 people tune it still wouldnt go so i done the screen and tune and now runs like a new one

Sorry for the late reply on this one guys, it was a project on the back burner. The screen was good and turned out to be the metering. i did bend it out a ittle when i stripped it down(it doesn't take much to throw out the metering as they are tiny). After a lot of tinkering and adjustments in small increments i got it right so all good now. Thanks for the help and advice. Feel free to close this thread.

Thanks for posting that bigted. As I'm sure you know, a thread with a clear outcome is much more useful to other people than one that just leaves them in midair.

I'll close the thread. If anyone needs to post to it, just send a PM to a moderator.