026 won’t run

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axe2fall

axe2fall

Hound runner
Joined
Feb 6, 2012
Messages
359
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Location
VIRGINIA ! . . the mother of presidents
Hi guys, it’s been awhile since I’ve been on here but I am stumped and frustrated as is my buddy who needs his saw back.
He has threatened to let someone else take a look and I just can’t have that !
So here I am begging for clues…..
The saw is a rebuilt 026 with a new OEM MS260 jug. Compression release is plugged. Rebuilt carb. Exhaust matched to muffler and polished Muffler opened up, Base gasket delete, Compression 180 cold. It’s a ripping saw. Or it was.
I gifted this to my buddy 8 years ago and he has prob put 8-10 tanks thru it yearly. Never any problems until last fall. It became hard to start when cold. And now it won’t start at all. Not even a pop. It has good spark. Clean filters and muff screen. Good clean fuel. Piston looks great on exhaust side. I didn’t check the intake side but compression is good.
Fuel in the cylinder will get it to pop and briefly idle. Fuel thru the carb throat has no effect which make no sense to me. I’ve adjusted the Waldbro 194 carb …many times. Even tried a known good carb which is on it now. 3 different plugs. Nothing changes.
What am I missing ?
 
There is a reason why test procedures should be carried out first before randomly swapping out parts, that can get rather costly and to keep guessing why the saw won`t run will take up more time and usually parts changing. It really comes down to the basics, spark at the right time, enough compression and fuel mix in the cylinder. even if a saw has the impulse line off it will fire up with mix induced into the cylinder but not run long. Leaking seals the same but with a bad vac leak the engine cannot produce enough signal to the fuel pump side of the carb to pull fuel from the tank. If it fires then the timing is not off as in a sheared flywheel key and even if the exhaust screen is plugged solid the engine will fire up but not throttle up. A ripped intake boot will usually allow the engine to start but race due to the air leak. I have had one come in that would run sort of but not tune, the boot was completely off the cylinder flange, it was held sort of tight against the cylinder so it would pull mix and start.Best to run some tests before swapping more parts, vac and pressure tests save a lot of time and frustration.
 
Of course it's always best to do the testing before ordering a bunch of parts. OP seemed to be in a hurry so I gave my opinion of what might be his problem. Since it popped but would not run it sounded like it might have slipped time slightly. Other things might cause it too but he seemed to have most of it covered. On many Stihl models like this one I generally have spare parts, like ignition modules so if that's suspected I try a known good one, like OP did with carbs.
 
When the engine fails to pop after squirting fuel into the carb, is the plug wet or dry?
Is the choke part of the air filter on that saw and if so, are you sure it is closing properly?
You say the saw will start and run briefly on idle after squirting fuel into cyl. Is your normal starting procedure right? You should never expect a cold saw to start on closed throttle (idle) position. Fast idle setting and choke completely closed is good. If it fails to even pop after a number of pulls, you have to remove the plug and see if it is wet or dry.
 
pioneerguy600 said:
There is a reason why test procedures should be carried out first before randomly swapping out parts, that can get rather costly and to keep guessing why the saw won`t run will take up more time and usually parts changing. It really comes down to the basics, spark at the right time, enough compression and fuel mix in the cylinder. even if a saw has the impulse line off it will fire up with mix induced into the cylinder but not run long. Leaking seals the same but with a bad vac leak the engine cannot produce enough signal to the fuel pump side of the carb to pull fuel from the tank. If it fires then the timing is not off as in a sheared flywheel key and even if the exhaust screen is plugged solid the engine will fire up but not throttle up. A ripped intake boot will usually allow the engine to start but race due to the air leak. I have had one come in that would run sort of but not tune, the boot was completely off the cylinder flange, it was held sort of tight against the cylinder so it would pull mix and start.Best to run some tests before swapping more parts, vac and pressure tests save a lot of time and frustration.
Click to expand...
I agree and understand what you are saying. Although sometimes it’s easier to swap a part than to test. Especially if you have the parts. I tried a carb and plugs to rule those out because it was quick and easy. I can check the rubber but i always used OEM so don’t think they have deteriorated… but they could have slipped.
I’ll check the timing next for those reasons….
There is the possibility that I deleted the flywheel key ! …It’s been 8 years and I’m kinda old.

I cannot think of a reason it will pop and briefly run from fuel squirted in the cylinder but not thru the carb
 
Old2stroke said:
When the engine fails to pop after squirting fuel into the carb, is the plug wet or dry?
Is the choke part of the air filter on that saw and if so, are you sure it is closing properly?
You say the saw will start and run briefly on idle after squirting fuel into cyl. Is your normal starting procedure right? You should never expect a cold saw to start on closed throttle (idle) position. Fast idle setting and choke completely closed is good. If it fails to even pop after a number of pulls, you have to remove the plug and see if it is wet or dry.
Click to expand...
It’s past all of that. The saw will start and run briefly but only if I put a squirt of mix directly in the cylinder. Same squirt thru the carb has no effect. I’ve done this several times in different order with different plugs and a known good carb. Same. Ive tried to eliminate the coincidence of this but it still could be one. I’m definitely going to inspect the intake boot and check the timing next
thanks
 
axe2fall said:
I agree and understand what you are saying. Although sometimes it’s easier to swap a part than to test. Especially if you have the parts. I tried a carb and plugs to rule those out because it was quick and easy. I can check the rubber but i always used OEM so don’t think they have deteriorated… but they could have slipped.
I’ll check the timing next for those reasons….
There is the possibility that I deleted the flywheel key ! …It’s been 8 years and I’m kinda old.

I cannot think of a reason it will pop and briefly run from fuel squirted in the cylinder but not thru the carb
Click to expand...
There may be times where it is easier but just guessing can also just lead to more expense. I can relate more stories about guessers costing clients huge sums of money. times it cost more for a rebuild than a new saw would cost but that would require a book length ramble. I did mention about a saw coming in and the intake boot was not connected to the cylinder, lets go with that one. The saw had been taken to a local repair shop, that shop really did not repair saws but most often had others do the work and then return the saws to said shop, the owner would call the client and say your saw is repaired come get it. The shop would add 20% to the bill for their involvement and never tell they had not done the work. The owner of the saw in this story told the shop owner it was low on power and would not stay tuned, the saw owner felt the saw was old and had a lot of hours on it so it likely needed a new P&C, the shop owner had no test gear but agreed to install a new OEM piston and cylinder set on the saw. Without any testing and for once he went ahead and did the swap himself thinking that he could not go wrong using all new OEM parts, he usually did not do any real repair work, change a plug or maybe a carb kit was about all he ever did on his own. The P&C set got installed and the saw started inside the shop, ran for about 30 seconds and shut down, owner was called in and told the saw was started but it would need to be tuned when there was some wood to be cut and tune it then. Well the saw owner could get the saw to start but couldn`t tune it to stay running no matter how the screws were set, he was in a hurry to get his winters wood cut up and needed a running saw, after telling the shop owner the saw was not running right the shop told him it would be a coup[le of weeks before they could look at it again, if it needed more parts it could be several more weeks before they could get it back to him.The owner tried to impress how important it was for him to have the saw running so the shop owner gave him my number to see if I had time to look at it. I did and so the saw was dropped off to me and I called the shop to see what they had done to it. The saw would fire up but not run consistently so I tried the carb settings, H was 4 1/4 turns out, L was out 1 1/2 so I adjusted them the way I usually do at 3/4 turn out for the H and around 1 out for the L. So I began to investigate, found the manifold not connected and figured ahaha, so connected that and the saw would run better but still not right so out came the test gear and lo and behold it would not hold vac or pressure, something was up so deeper teardown and soapy water showed that the case gasket was leaking badly plus the impulse hose at the cylinder base was too loose, crank seals were tight and base gasket no problem, it was new. So now I had to split the crankcase and replace the gasket, easy peasy,a new impulse line and back together it went, started up and ran nicely, tried it in wood and was satisfied it was cutting well. I believed that the crankcase gasket plus the loose impulse was the problem from the outset but no test had been done, just a guess the P&C were worn out between two parties that probably should not be making such decisions. I took the saw back and retrieved the original P&C that I now run on one of my own saws, it still makes 142 lbs comp so by no means worn out. When I told the shop owner what I had found his reaction was , its an old saw anything could be wrong with it, he had told the saw owner it would be best for him to buy a new saw from the outset. The owner would rather spend the $300. to have it fixed but in reality the saw ended up costing over $500. but a simple test at the outset would have cost less and saved time to. A long read but I could not give the details in a shorter form.
 
Since you swapped plugs already, while doing so did you visually check for spark? Easy enough plug out and connected and grounded to case, pull and should have good spark every rotation. free to check and as they say, 99% of fuel carb problems are electrical :D
 
pioneerguy600 said:
There may be times where it is easier but just guessing can also just lead to more expense. I can relate more stories about guessers costing clients huge sums of money. times it cost more for a rebuild than a new saw would cost but that would require a book length ramble. I did mention about a saw coming in and the intake boot was not connected to the cylinder, lets go with that one. The saw had been taken to a local repair shop, that shop really did not repair saws but most often had others do the work and then return the saws to said shop, the owner would call the client and say your saw is repaired come get it. The shop would add 20% to the bill for their involvement and never tell they had not done the work. The owner of the saw in this story told the shop owner it was low on power and would not stay tuned, the saw owner felt the saw was old and had a lot of hours on it so it likely needed a new P&C, the shop owner had no test gear but agreed to install a new OEM piston and cylinder set on the saw. Without any testing and for once he went ahead and did the swap himself thinking that he could not go wrong using all new OEM parts, he usually did not do any real repair work, change a plug or maybe a carb kit was about all he ever did on his own. The P&C set got installed and the saw started inside the shop, ran for about 30 seconds and shut down, owner was called in and told the saw was started but it would need to be tuned when there was some wood to be cut and tune it then. Well the saw owner could get the saw to start but couldn`t tune it to stay running no matter how the screws were set, he was in a hurry to get his winters wood cut up and needed a running saw, after telling the shop owner the saw was not running right the shop told him it would be a coup[le of weeks before they could look at it again, if it needed more parts it could be several more weeks before they could get it back to him.The owner tried to impress how important it was for him to have the saw running so the shop owner gave him my number to see if I had time to look at it. I did and so the saw was dropped off to me and I called the shop to see what they had done to it. The saw would fire up but not run consistently so I tried the carb settings, H was 4 1/4 turns out, L was out 1 1/2 so I adjusted them the way I usually do at 3/4 turn out for the H and around 1 out for the L. So I began to investigate, found the manifold not connected and figured ahaha, so connected that and the saw would run better but still not right so out came the test gear and lo and behold it would not hold vac or pressure, something was up so deeper teardown and soapy water showed that the case gasket was leaking badly plus the impulse hose at the cylinder base was too loose, crank seals were tight and base gasket no problem, it was new. So now I had to split the crankcase and replace the gasket, easy peasy,a new impulse line and back together it went, started up and ran nicely, tried it in wood and was satisfied it was cutting well. I believed that the crankcase gasket plus the loose impulse was the problem from the outset but no test had been done, just a guess the P&C were worn out between two parties that probably should not be making such decisions. I took the saw back and retrieved the original P&C that I now run on one of my own saws, it still makes 142 lbs comp so by no means worn out. When I told the shop owner what I had found his reaction was , its an old saw anything could be wrong with it, he had told the saw owner it would be best for him to buy a new saw from the outset. The owner would rather spend the $300. to have it fixed but in reality the saw ended up costing over $500. but a simple test at the outset would have cost less and saved time to. A long read but I could not give the details in a shorter form.
Click to expand...
I get ya. Different scenario here but I get ya.
 
guysmiley said:
Since you swapped plugs already, while doing so did you visually check for spark? Easy enough plug out and connected and grounded to case, pull and should have good spark every rotation. free to check and as they say, 99% of fuel carb problems are electrical :D
Click to expand...
Yeah. .. three plugs, a Bosch, a NGK and a Champion all showed excellent spark
 
pioneerguy600 said:
There may be times where it is easier but just guessing can also just lead to more expense. I can relate more stories about guessers costing clients huge sums of money. times it cost more for a rebuild than a new saw would cost but that would require a book length ramble. I did mention about a saw coming in and the intake boot was not connected to the cylinder, let’s go with that one. The saw had been taken to a local repair shop, that shop really did not repair saws but most often had others do the work and then return the saws to said shop, the owner would call the client and say your saw is repaired come get it. The shop would add 20% to the bill for their involvement and never tell they had not done the work. The owner of the saw in this story told the shop owner it was low on power and would not stay tuned, the saw owner felt the saw was old and had a lot of hours on it so it likely needed a new P&C, the shop owner had no test gear but agreed to install a new OEM piston and cylinder set on the saw. Without any testing and for once he went ahead and did the swap himself thinking that he could not go wrong using all new OEM parts, he usually did not do any real repair work, change a plug or maybe a carb kit was about all he ever did on his own. The P&C set got installed and the saw started inside the shop, ran for about 30 seconds and shut down, owner was called in and told the saw was started but it would need to be tuned when there was some wood to be cut and tune it then. Well the saw owner could get the saw to start but couldn`t tune it to stay running no matter how the screws were set, he was in a hurry to get his winters wood cut up and needed a running saw, after telling the shop owner the saw was not running right the shop told him it would be a coup[le of weeks before they could look at it again, if it needed more parts it could be several more weeks before they could get it back to him.The owner tried to impress how important it was for him to have the saw running so the shop owner gave him my number to see if I had time to look at it. I did and so the saw was dropped off to me and I called the shop to see what they had done to it. The saw would fire up but not run consistently so I tried the carb settings, H was 4 1/4 turns out, L was out 1 1/2 so I adjusted them the way I usually do at 3/4 turn out for the H and around 1 out for the L. So I began to investigate, found the manifold not connected and figured ahaha, so connected that and the saw would run better but still not right so out came the test gear and lo and behold it would not hold vac or pressure, something was up so deeper teardown and soapy water showed that the case gasket was leaking badly plus the impulse hose at the cylinder base was too loose, crank seals were tight and base gasket no problem, it was new. So now I had to split the crankcase and replace the gasket, easy peasy,a new impulse line and back together it went, started up and ran nicely, tried it in wood and was satisfied it was cutting well. I believed that the crankcase gasket plus the loose impulse was the problem from the outset but no test had been done, just a guess the P&C were worn out between two parties that probably should not be making such decisions. I took the saw back and retrieved the original P&C that I now run on one of my own saws, it still makes 142 lbs comp so by no means worn out. When I told the shop owner what I had found his reaction was , its an old saw anything could be wrong with it, he had told the saw owner it would be best for him to buy a new saw from the outset. The owner would rather spend the $300. to have it fixed but in reality the saw ended up costing over $500. but a simple test at the outset would have cost less and saved time to. A long read but I could not give the details in a shorter form.
Click to expand...
What a disgrace of a shop. Either do the job right or don’t do it at all.

Glad he was passed on to you and you sorted it out correctly.
 
Captain Bruce said:
.
Click to expand...
The suggestion that you pressure test the rings, & crank seals, and vac test the jug, for induction leaks? Those are also basic small engine mechanics, Small Engine Class 2.0. Those tests should have already been performed, with proper equip't.

If this is a sit on your hands for months post.............get off your ass.
 
Well I'd say he's been given every suggestion there is for a fix at this point.

Why not just let the fella get back with us in his own time and not belittle him about it.

After all, he merely asked for our help. We've all been there gents.
 

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