Chain Saw Dies When Cutting

[tslockbo]

Hey there everyone,

I have an interesting problem with a Stihl 026. It starts and runs fine. However, as soon as I try to cut wood, it chokes and dies. The weird part is that it will cut fine if I use the top of the bar with upwards pressure from the bottom of the log.

I cleaned the air filter which had become contaminated with dust on the inside of the filter. The L screw is turned clockwise one turn from a seated position. The saw idles fine without stalling.


Any suggestions?

 

[Umbellularia]

I have an interesting problem with a Stihl 026. It starts and runs fine. However, as soon as I try to cut wood, it chokes and dies. The weird part is that it will cut fine if I use the top of the bar with upwards pressure from the bottom of the log.

Bad impulse line or intake boot? Cutting with the top of the bar causes the crankcase and rear handle/fuel tank/carb to twist the opposite way from normal.

 

[redunshee]

Bad impulse line or intake boot? Cutting with the top of the bar causes the crankcase and rear handle/fuel tank/carb to twist the opposite way from normal.

I've never seen this situation but it seems to make sense. Either way if its the impulse line or boot you had better fix it quick or risk lean burning up your saw.

 

[D&B Mack]

Without actually cutting, lean your saw forward and rev for a while. Then lean it back for a while and do the same. If it cuts out when you lean it forward, then you probably have a bad fuel line and it is the angle of cut and the fuel in your tank.

 

[tslockbo]

Bad impulse line or intake boot? Cutting with the top of the bar causes the crankcase and rear handle/fuel tank/carb to twist the opposite way from normal.

Thanks for the reply. I take it the "pickup boot" is the what Stihl calls the pickup body?

 

[H 2 H]

Thanks for the reply. I take it the "pickup boot" is the what Stihl calls the pickup body?

Here is the part # 1121 141 2200 Manifold/intake boot

 

[nstueve]

where is your "H" needle set? or do you even have one? Some of the 024/026's had fixed "H" jet carbs. if you don't have a H-screw to adjust I would get a fully adjustable carb. The "h" screw controls your saws power at full throttle. to far in and you'll be running lean and to far out and you be running to rich and flooding the engine.

 

[tslockbo]

Ok,

Latest update. I took the saw apart. The intake boot was good but the impulse line was a little dried out and hard. I could see where it looked like it was getting pinched. I replaces both the impulse line and intake boot as well as the fuel line and filter while it was all apart.

I put everything back together and the saw would not run well I finally got it to start and idle by turning the H till it was almost seated. If I give it gas, it will stall. If I turn the H screw clockwise till it is seated, i can rev the engine although it is not running smoothly.

I took everything apart again to be sure the intake boot and impulse line were not damaged during installation and seated properly. Everything looked good. The only way I can give it gas without it stalling is if the H screw is seated. I made sure the plug was clean and gapped at .02". the air filter is new and the choke is working fine in it.

Any ideas?

 

[o8f150]

Ok,

Latest update. I took the saw apart. The intake boot was good but the impulse line was a little dried out and hard. I could see where it looked like it was getting pinched. I replaces both the impulse line and intake boot as well as the fuel line and filter while it was all apart.

I pout everything back together and the saw would not run well I finally got it to start and idle by turning the H till it was almost seated. If I give it gas, it will stall. If I turn the H screw clockwise till it is seated, i can rev the engine although it is not running smoothly.

I took everything apart again to be sure the intake boot and impulse line were not damaged during installation. Everything looked good. The only way I can give it gas without it stalling is if the H screw is seated.

Any ideas?

you are messing with the wrong screw for idle,, run both the l and h metering screws all the way until lightly seated then back both out 1 1/4 turns

 

[tslockbo]

you are messing with the wrong screw for idle,, run both the l and h metering screws all the way until lightly seated then back both out 1 1/4 turns

I started with 1 turn CCW from seated for both the L & H per the owners manual and could not get it to start. I could only get it to start by setting the H to 1/2 turn CCW from seat could only get it to rev with the H screw seated.

 

[o8f150]

if it would only go wot with it seated then you have problems inside the carb,, its running way to rich

 

[tslockbo]

if it would only go wot with it seated then you have problems inside the carb,, its running way to rich

I have a rebuild kit on order. Should get it on Friday or Saturday. In the meantime, I took the two covers off the carb and cleaned out a little silt of the screen. The needle was clean as was the seat for it. should I take the L & H screws out completely to see if there is any gunk in there?

By the way, what is WOT?

 

[sony1998]

WOT= wide open throttle

 

[tslockbo]

if it would only go wot with it seated then you have problems inside the carb,, its running way to rich

Any suggestions on what could be causing it to run rich?

 

[tslockbo]

OK,

Things are looking better this morning. I took the carb off and apart again. This time I took the L and H screws out and blew their holes out with a compressor. I put everything back together again and it was still choking. I started it up again without the air filter this time since that was another thing I replaced. This time it started up and ran much better. I let it run till it was good and hot and put the air filter back on. I was able to get WOT with the H set to slightly more than half a turn CCW from seat. The L is 1 turn CCW from seat.

It is running like a champ now when not cutting. However, when cutting, it is stalling again. Is it time for a compression test? Anyone have any ideas?

 

[Umbellularia]

It is running like a champ now.

Great to hear that! My first saw was/is an 026. At the time I knew nothing about saws - a neighbor told me to get that model...

I was able to get WOT with the H set to slightly more than half a turn CCW from seat.

I think spec for H is 7/8 CCW. Have you had this saw since new - or, has anyone else worked on it? I suspect that the impulse line had started leaking some time back. In response, someone might have richened the saw up a bit - perhaps by adjusting the little lever that lifts the carb needle.

My 026 developed a small leak in the flywheel side crank seal. Initially I tried to tune it out via the carb adjustments. Once the seal leak got bad enough to definitively diagnose it, I replaced the seals. At that point I discovered the saw was tuned too rich. It sounds like something similar happened with your saw.


Now that your saw is running good, I'd suggest you check the AntiVibe bushings. Perhaps that are getting sloppy - allowing more movement between the carb and crankcase. This (and age) might be what damaged the impulse line.

 

[tslockbo]

Great to hear that! My first saw was/is an 026. At the time I knew nothing about saws - a neighbor told me to get that model...



I think spec for H is 7/8 CCW. Have you had this saw since new - or, has anyone else worked on it? I suspect that the impulse line had started leaking some time back. In response, someone might have richened the saw up a bit - perhaps by adjusting the little lever that lifts the carb needle.

My 026 developed a small leak in the flywheel side crank seal. Initially I tried to tune it out via the carb adjustments. Once the seal leak got bad enough to definitively diagnose it, I replaced the seals. At that point I discovered the saw was tuned too rich. It sounds like something similar happened with your saw.


Now that your saw is running good, I'd suggest you check the AntiVibe bushings. Perhaps that are getting sloppy - allowing more movement between the carb and crankcase. This (and age) might be what damaged the impulse line.

Laura,

Have you seen the latest post? Could seals be my problem on the continued stalling under load? I remember reading on another post that bad seal are a common problem on the 026. Should I have a compression test done?

 

[dpbr1975]

Have you checked you piston for scoring yet, i knew mine had a scored piston and cylinder and would not run very well no matter what I did, it had no power at WOT and had to turn up the idil to make it stay running. Maybe pull you muffler and see if its scored to make sure, I talked to the stihl dealer and he said that no matter what you do to that carb it will not run worth a damn with a scored p/c. Yes mine did idil but once I replace my P/C I turned each H and L screws one turn out and It runs great with my power back. I did replace the oil seals too. Ohio state perfect season !

 

[tslockbo]

Have you checked you piston for scoring yet, i knew mine had a scored piston and cylinder and would not run very well no matter what I did, it had no power at WOT and had to turn up the idil to make it stay running. Maybe pull you muffler and see if its scored to make sure, I talked to the stihl dealer and he said that no matter what you do to that carb it will not run worth a damn with a scored p/c. Yes mine did idil but once I replace my P/C I turned each H and L screws one turn out and It runs great with my power back. I did replace the oil seals too. Ohio state perfect season !

No scoring. Shiny & smooth.

 

[Umbellularia]

Have you seen the latest post? Could seals be my problem on the continued stalling under load? I remember reading on another post that bad seal are a common problem on the 026. Should I have a compression test done?

Oops! I missed the part where you said it still stalled when cutting. I suspect that you have H closed too far.

Spec for the carb settings seems to be 1 turn CCW for both H and L. I found on my 026 that I really had to start from the standard settings when adjusting the carb. With three adjustments (H, L, and LA) available, and all of them interacting, there are a lot of combinations that seem to be almost correct but aren't.

Trying to tune out my saw's crank seal leak resulted in more L and less H (and probably lower LA). Having to do that might be a clue to a leak.

I didn't do a pressure/vacuum test before replacing the crank seals. The symptom of positional sensitivity implied a leak. (The saw ran fine bucking, but not felling.) When I got the flywheel off, it was obvious the seal behind it was leaking - there were small blobs of oil (aka mix oil) squeezing out of the seal.