stihl chainsaw help

just acquired a very like new MS290 farm boss. it has sat for about a year and is not oiling. I have run the ajuster both way many times.
I pulled the bar and cleaned it. I applied vacuum to the oil port hoping to "unstick" a checkvalve or whatever. I squirted a touch of perc in there and blew it out. I drained the oil and it looked clean. I added ATF (low vis, high detergent) and pressurized the reservoir trying to get oil to weep out of the hole. I ran the saw at mid speeds with the tranny oil and still no oil. I drained the atf out and am ready to tear it down, unless someone has other ideas.

I might try long-term vacuum on the little hole with a vacuum pump I have for servicing air conditioners.

I also wanted to slip a tube over the oil pickup and blow on it to try to pressurize the suction side of the pump.

Anyone got a trick for this? Is there a common part that fails in these? it is cold, but the first thing I did was warm the saw in the sun and try it with bar oil--then i did all that stuff above...

need oil, would rather not disassemble...

Thanks...

ms

thanks guys:

i can certainly take it apart.

I am pissed that Stihl won't sell service manuals (maybe the dealer will, I don't know. I see them on ebay. I hoped to download, but I realize that is a lot to ask). i pay a lot for automobile service manuals from the manufacturers.....anyway, i don't need it. I have a lot of this type of experience. i would rather have a manual that told me how to re port the cylinder ports for 30% more horsepower (power to the 13+ pound weight of this is not fantastic), anyway...

I will try a lighter oil or fuel, then I will tear down. I am glad to hear that when this happens, the pump needs a cleaning, and not a replacement.

On another note, I gave this some thought since I started trying to fix (after purchase) and I am starting to suspect the previous owner ran it dry becasue:

the saw looks very new. looks like 5 tanks. all paint is on bar, bar was right side up and chain was loose. i ran before i bought and told seller "it is no oiling, and i wanted longer bar, therefore, lower price." now I think back, he seemed surprised when i mentioned that the saw should dump one tank of oil for one tank of fuel, more or less. maybe a bit less with the fancy stihl chain and crap.....and, he was on his second chain--both chains were used, but neither looked bad. they had never been filed. so I wonder if he ran out of oil and it cut poorly so he changed chains and stretched the second one out......

anyway, the bar is NOT discolored/peeling paint from super heat--so maybe my theory has a hole in it.

I will dump a little fuel in there and let her sit and run lightly and stuff...

BTW, does anyone know how the pump works? one of you said you cleaned one? is is a piston? plastic? what drives it? engine or chain train? diaphrage? ecentric cam? I saw a picture of a deal with a bent wire looked like a return spring for a diaphragm or so,......

Just wondering what to expect.

Thanks for the ideas!

I added a touch of camp fuel to the residue of bar oil and tranny oil in there and shook it around. ran at mid speeds and nothing. I will let it sit a while and try later....

ms

no luck, on high vac now trying to suck the fuel through to loosen things up.

Where is the pump in there, what is the most direct way to access, do I need to remove the clutch?

Thanks,
ms

Great, thanks.

Does the clutch screw onto the crank with L.H threads? seem like it should be LH or it would "drive" right off.

What is the preferred way to hold the crank? knotted rope in spark plug hole? special fixture in hole? some other way?

thanks again,

ms

i believe the pump in the ms290 is in a similar location because the oil pickup tube heads that direction, and the adjuster screw in under there.

ms

i have it apart. I was able to get the clutch off with the scrench tool that i removed the plug with and "roped" the cylinder.
the pump was badly jamed and the nylon worm stripped. I freed up the pump, but the worm won't engage it.
I will shop ebay for a worm, or else call a local stihl shop Monday.

Thanks for everything...

i already found parts online. I might go big on this one:

used worm (future spare to toss in the box)
new worm
rim drive bell and sprocket
extra sprocket for 3/8 pitch
used bar and chain (longer, 3/8)
service manual
extra bar nuts
extra spark plug.....

the stuff clogging the pump was very hard. it reminded me of congealed castor oil (from high-nitro model fuel). it was green, too. some like grease, some like hard glue. when I bought the saw, the seller handed me a half-gallon of ace hardware bar and chain oil. I will forever be suspicious of this now...