MS 310 running issue...

[mrcaptainbob]

Right while making the first notch cut the 310 bogs and quits. Restarting was a challenge.Grabbed a few times at full choke. (this was after about an hour or two work. Saw was warmed up.) Took it back to the shop and did a good  (to me) job of air cleaning everything. Inside and outside the air filter, Air cleaned the entire saw body with chain and bar removed. Cleaned around the carb and inspected inside carb. All seemed fine. Restarting is still an issue. Full choke and it starts and stumbles. Quickly advance to half choke and it finally seemed to run okay. Advanced it to full open choke and it seemed okay. Back to the notch cut. It ran fine. Did up a 40' 16" oak log every five feet and it ran great. Advanced to the next tree and it started the stuff again. Appears that it happens when tipped on it's side. Excpet that it is so hard to start. Finally got it to stumble again at full choke. Then went to half choke again, then to full open. But it would only keep running if the throttle was constantly dinked with. Will not maintain rpm's at any throttle setting. Only if the throttle is constantly messed with. What do I need to do to get this back to it's old reliable self? I'm lost with out this helper!

[dougand3]

Lotsa symptoms here. Start checking simple, free things. Muffler screen clogged? Fuel pickup stays IN fuel? Fuel line in good shape? Tank Vent works? Remove and disassemble carb to check diaphragms and needle/seat. Can get a new clone carb for ~$15 online - I'd do that before rebuilding the carb.

[sawguy21]

I would be looking for a cracked impulse or fuel line.

[Texas-Jim]

As was said lot of times its a bad hose, if its in tank it may be not staying in fuel well. If its impulse or fuel line often turning on side causes it to stumble mainly because the AV allows movement and hose leaks. Iv found before doing anything costs money do an engine check, stihl actually has a written version. Check hoses ,spark, look at piston and spark arrestor. Many time just a good eye will see the grimlin.

[MickMac]

Any saw I get in that dies on her side Ill go to crank bearings first and go from there..

[mrcaptainbob]

Thank you for the suggestions. I'll be looking at it this evening...

[mrcaptainbob]

Took the carb apart was AMAZED at the crud in there. Interesting how it gets past the filter. I try to be fastidious about the filters and such. Amazing. Anyway...it did seem to run much better ... at that point. But this morning it would not even start. Since there's a tremendous amount of oily...umm...stuff around the clutch cup I'm thinking your suggestions about a crank seal are correct. I'll be looking at Utube for the how-to on that. I hope that can be done without splitting the case.
By the way, this saw, although a real great running machine, has always been very, very difficult to start. By that I mean in pulling the rope. It's as if it has about 300psi compression. It catches severe enough at times to put a serious shock in the wrist. Any ideas on that? I can deal with it if it means disrupting an otherwise great running unit....

[mrcaptainbob]

Seemed to run better after new rank seals. As for the oil around the clutch cup it appears it's from a compromised and very well worn bar oil pump. I have a new one along with a new clutch cup and such (stated in thread about clogged bar oil passages...) that will be installed later next week.
Thanks for those suggestions. Progress is being made. With your help.