Stihl chain saw: Fuel problem?

[nrwayne]

My Stihl 021 chain saw has always been hard to start when it's cold. Now it doesn't start at all, but it will kick if I shoot starting fluid into the carburetor. The local repair shop didn't even look at it. Just said the carburetor's gummed up and they'll be happy to replace it for $175. Astronomical, in my opinion. I suspect that this is a reasonably simple engine to repair and am willing to attempt to correct the problem myself. I'm guessing that the job will require checking and cleaning out the fuel system, but beyond that I need some suggestions. Please let me know what ideas you may have that will help me get this done. Thanks.

[Randy]

You might be able to simply remove the carb and soak it in a solvent for a day or two. A carb degunking solvent like what you can get at your local auto parts store (e.g. Gumout, Deep Creep) ought to do the trick.

If you're fighting varnish, you'll probably have to scrub out the carb bowl and jet(s). Carbs for 2 stroke engines are pretty simple. Just take a toothbrush or maybe a conical dental brush and thoroughly scrub out the bowl and float of the carb while flushing liberally with a carb cleaner solvent.

You may have to remove the jet's needle valve to clean it (and its seat). That's the most likely victim of varnish. If you do that, try to mark the needle adjustment screw somehow (or count the number of turns required to remove it) before removing it. That way, you have a fair chance of getting it put back together properly when you reassemble.

Also make sure that gas *is* flowing from the tank. There may be crap in the line, the gas line filter, or there may be an obstruction in the tank.

Finally, get some new gas. Higher grade gas is likelier to help dissolve gunk and varnish all by itself.

Of course, do all of this outside in a well ventilated area.

Or you can just buy a new carb and replace the old one. It'll probably be easier than cleaning the old carb and a lot cheaper than the $175 for shop labor.

These links may be helpful:

Randy

[nrwayne]

Thanks. I think a bit of elbow grease will get this job done far less expensively than asking to be ripped off by the local thief.