Hey guys, I am totally stuck at this point and decided to drop my Stihl MS250 at the local shop to have them give it a shot. Wrote them a detailed note and they are 2 weeks out, but figured I'd post here in the meantime to get you all's opinion.
This issue has me baffled and annoyed to no end. The saw runs beautifully despite being nearly 2 decades old, except for this one issue that has happened for a while now.
When cutting into a log, at full throttle, and then releasing the throttle with the bar still in the log, the saw will stall out. When it doesn't stall out, the idle drops very low, as if it's about to stall. After about 5-10 seconds, if it doesn't stall, idle RPMS climb back up to where I have them set.
This only happens when the bar is still in the log, touching wood against the chain. Cannot replicate it by revving in the air and letting off the throttle.
Starts perfectly, will sit there an idle all day long. Usually starts on just 1 pull. But when it stalls out like this, restarting it takes like 6-8+ pulls.
I've tried everything. The obvious has already been done - spark plug, air filter, tuning the carb screws - with no luck. I even replaced the clutch, as a user on here way back thought maybe it was the clutch sticking. Their theory made sense - chain touching log, so if clutch is sticking then the stopped chain will cause the engine to stop turning too. However, new clutch that is totally clean doesn't help. I also inspected all the fuel lines and as far as I can tell, no cracks or leaks. They all seem pliable and when pressing the purge bulb I don't see any fuel or bubbles or anything leaking out.
I actually had it at the shop a few months ago for an unrelated issue, they tore apart and cleaned the carb and changed the diaphragm, and it actually ran quite well for a few weeks before I put it away. Month or so later, it's back to this bull.
Any ideas? I'm about at my wits end and just going to sell the saw and buy a new MS261 or something. Let me know what yall think, thanks
I actually got a video of it stalling out. Check it out: cutting into log at full throttle, release throttle part way through, saw dies.
Thanks for this, I'll remember this going forward. So this helps the bar stay oiled? I suppose it has nothing to do with stalling?It's not necessary to pull the bar all the way out of the cut, just lift the chain off the wood, keeping the bar in the kerf and the chain turning. When cutting nice green softwood this is completely unnecessary unless, of course, your oiler is not putting out enough oil. It can be a real help in dry hardwood or pitchy pine such as the pinyon we have here in the southwest.
Hoping this isn't the case but very well could be. Saw is nearly 2 decades oldHere is my .02cents worth. After a full power burn unburned mix accumulates inside the crankcase. This is now flooding or exceptionally rich and slowing the saw down. What causes this? Worn rings. In a normal position, all is well and saw runs normally. Ken
Thanks for the suggestion pal. So to test, plug the line between carb and bulb, and run her and see if the issue goes away? I'll definitely do thatA bad primer bulb will cause the stalling symptoms you are experiencing. Carburetor will suck air and engine will stall out. To test, you can plug line between primer bulb and carburetor. The primer bulbs do not age gracefully and it is due for replacement.
I think you still have a carb issue.I actually had it at the shop a few months ago for an unrelated issue, they tore apart and cleaned the carb and changed the diaphragm, and it actually ran quite well for a few weeks before I put it away. Month or so later, it's back to this bull.
That chain is duller than the dirt that dulled it!
Dying out like that is a sign that the saw is too rich coming off of WOT. May also be old gas. Get some fresh from the pump non-E gas and make a new batch of 50:1 mix.
1. Clean/replace air cleaner. SOFT paint brush from outside followed by non-chlorinated brake cleaner from the inside.
2. Remove and burn the spark screen from the muffler with a torch.
3. Now you are ready for carb tuning. Set the "H" to full CCW limiter stop.
4. Set the "L" to 1-turn out from lightly seated. Should be printed on the AF cover. Leaning out the "L" slightly (CW) may help the idle recovery issue.
5. If this doesn't improve the running put a new OEM (ONLY) kit in the carb or replace the carb as a last resort.
Keep in mind that a new carb will need to be tuned properly and then the "H" limiter punched down.
I would test the coil. Anytime I get voodoo problems like this it's often the coil. By "test" I mean try a different coil. Sometimes they only short in very specific circumstances and they'll test fine on the bench. I'd also try adjusting the high speed mixture screw.
Looking at your out of place av mounts/plugs, I would check the impulse line and intake boot. The impulse line is notorious for pulling off of the orange nipple, and an av mount problem would enhance that. Also hard on the intake boots.
Thanks for the input. I tried rebuilding the carb last time and royally bugged it up. I'm not good with teeny parts haha. I went for option 4 and bought a brand new OEM Stihl carb instead, it was only around 12 bucks more than the chinese ones online. Funny enough, my main Stihl dealer quoted me $50.99 for an OEM carb, and said it would be 3 weeks out unless I paid something like 20 bucks more for 3 day shipping! Called the other Stihl dealer nearby that I've never been to, they quoted me $30.99 and would be here in 3 days, no shipping charge... I didn't realize that Stihl dealers can decide their own price / markup.I think you still have a carb issue.
1.Rebuild current carb completely
2.Obtain used Stihl carb and put a kit in
3.Purchase a Chinese carb and install it
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