Stihl 026 hard to start, bogs down easily

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JRP3

Feeling the Heat
Hearth Supporter
Sep 17, 2007
321
NYS
Picked up a used 026 with 18" bar. At first it wouldn't start so I took off the air cleaner which was all plugged and cleaned it up and got it going. It still takes a while to get it running when cold. It has a torn black rubber button or plug on top which I thought might be a compression release but it doesn't move when I push it. I put a new chain on it and it revs up nicely but a little way into a cut it bogs down badly, I can lean harder on my Makita UC 4000 electric. This is in a 12 inch log which I would think should be no problem for it. What do you think, too lean maybe?
 
I bet somebody along the way adjusted the hi and lo air adjustment screws out of whack. That is what I would look at SECOND.

First I would replace the spark plug unless you know it is good to eliminate that potential issue. According to the mechanics at my saw shop, the spark gap area of the plug can still look good while the material in the white glass part of the plug goes bad. I use NGK brand spark plugs.

Next items I would check would be the little rubber lines that go to and from the carb.
 
Yeah I was going to throw a plug in it, any idea of the gap? Any idea what the rubber plug/button is in the top of the saw? It looks like a screwdriver slot under the torn rubber. The parts diagram I downloaded calls it a slotted nut and insulator.
 
I think the top deal is a mount for the plastic. if i recall right, there is some sort of groove on the pin/bolt, and the plastic has a rubber grommer that snaps into the hole in the plastic, then over the bolt/pin. Basically, snap on mount for the plastic. the grommet cracks and one end spirals outward.
I know mine had that poking out and I fixed it, just don't recall how. I can look tonight.

k
 
Check everything mentioned so far & then you might look for a can of Seafoam. Use it as directed. Two-cycles get carboned up after a while & this will make it run poorly(if the air-fuel mixture is messed up, even more so). Seafoam will burn the carbon out..it'll produce lots of white smoke initially, but this will burn out. Warm the engine up, hit it with Seafoam, let it sit, restart & run it hard for a while.

I picked up a leaf-blower on ebay a couple years back. It ran pretty much how you've described your chainsaw...no surprise the guy sold it (probably figured it was worn out). I hit it with Seafoam a couple times & it's run great ever since.
 
the plug you mentioned is supposed to have a hole in it. under it is the threaded nut w/screwdriver slot that holds down the top cover of the saw.
 
fishboat said:
Check everything mentioned so far & then you might look for a can of Seafoam. Use it as directed. Two-cycles get carboned up after a while & this will make it run poorly(if the air-fuel mixture is messed up, even more so). Seafoam will burn the carbon out..it'll produce lots of white smoke initially, but this will burn out. Warm the engine up, hit it with Seafoam, let it sit, restart & run it hard for a while.

I picked up a leaf-blower on ebay a couple years back. It ran pretty much how you've described your chainsaw...no surprise the guy sold it (probably figured it was worn out). I hit it with Seafoam a couple times & it's run great ever since.

That Seafoam is good stuff. I put it in a 2002 Chevy one ton with one of those 8.1 liter jobs. The smoke rolled for a while but it sure ran better after it was over.
 
In my fishing-boating days I used to run Seafoam through the engines once a year...before I put them away for the season. I'd smoke out the neighborhood or landing for a couple minutes, but the engines ran like new afterwards. Sometimes things are so bad you need two applications (I used two on the blower I picked up).

A friend used a good amount of Seafoam on an older truck & it smoked so much that a neighbor of his called the fire department...they thought he lit his place up.
 
wildbillx8 said:
the plug you mentioned is supposed to have a hole in it. under it is the threaded nut w/screwdriver slot that holds down the top cover of the saw.
Yup that's what it is, I thought it was a push button with a hole worn in it or something.
 
fishboat said:
In my fishing-boating days I used to run Seafoam through the engines once a year...before I put them away for the season. I'd smoke out the neighborhood or landing for a couple minutes, but the engines ran like new afterwards. Sometimes things are so bad you need two applications (I used two on the blower I picked up).

A friend used a good amount of Seafoam on an older truck & it smoked so much that a neighbor of his called the fire department...they thought he lit his place up.

So this seafoam stuff works on outboards? Do you add it to the gas?
 
Whats does this Seafoam do? I have lots of stuff to put up for winter and was impressed with reference to seafoam. I live near a Napa store and they might have it...also a close by VIP.
 
Seafoam is a carb/combustion chamber/valve cleaner. It is one of the few that works effectively and safely in two strokes. Napa does carry it. Seafoam is a top knotch product that can really put life back into some heavily gummed up, carbonized engines. (works wonders on diesels too)
 
polaris said:
Seafoam is a carb/combustion chamber/valve cleaner. It is one of the few that works effectively and safely in two strokes. Napa does carry it. Seafoam is a top knotch product that can really put life back into some heavily gummed up, carbonized engines. (works wonders on diesels too)

Thanks for the tip! This forum is great!
 
Ok, threw in a new plug, gapped at .020, (though the old one looked ok, gapped a touch large at .025), same problem. Took a close look at the fuel line from the tank and found some cracks. No wonder it doesn't want to run, it's probably sucking in air. I think a new fuel line will fix me right up, the saw doesn't look very heavily used other than that. Looks as if it might be a pain to change, anyone know how far I need to break this thing down, any tips?
 
JRP3 said:
Ok, threw in a new plug, gapped at .020, (though the old one looked ok, gapped a touch large at .025), same problem. Took a close look at the fuel line from the tank and found some cracks. No wonder it doesn't want to run, it's probably sucking in air. I think a new fuel line will fix me right up, the saw doesn't look very heavily used other than that. Looks as if it might be a pain to change, anyone know how far I need to break this thing down, any tips?
take your time and change the fuel filter why your at it
 
I'm not much for snake oils, but seafoam is actually one that I believe works well. The directions on the can indicate you can use it in the crankcase as an oil additive, in the gas tank as a valve cleaner & stabilizer, or in the cylinders to clean carbon out of the head & rings. I've only used it on cylinders. Get the engine warm, spray seafoam into the carb until it kills out, let it sit 15-20 minutes, fire the engine up & burn out the smoke...repeat if needed.

Supposedly you'll get the same result by adding seafoam to the fuel, but I think the cylinder approach is a little more to the point.

note: I edited out the "pour it in the cylinder approach" as this could be problematic if you leave too much in the cylinder...spraying in the carb until it kills works well & is generally safer from the engines point of view.
 
Good Stuff on the Sea Foam Product...Now how is it best used? Sorry I'm just dumb about engine stuff?
JChang
 
Still fighting with this thing. New fuel line fixed the hard starting, now it starts right up, idles well, revs right up at first but still dies out after revving up, like it's running out of fuel. Let off and let it idle a little then I can rev it again then it bogs down again. I forgot to pick up a new tank pickup filter but took the old one off and tried running it without a filter but it still does the same thing so it's not the filter. Anyone know the proper way to adjust the high side carb setting?
One thing that may or may not be relevant, the new fuel line had a larger diameter section where it goes through the hole in the fuel tank than the old line. I asked the dealer about that and he said that's the way the new ones were and it would work fine. I greased it up and got it in but I wonder if squeezing through the smaller hole might be constricting the hole in the fuel line and not allowing enough fuel flow?
 
JRP,

Are you sure that it is starving for gas?

My 028 is acting in a similiar fashion but mine is that it is getting overloaded with fuel I can tell by looking at the air filter which gets Damp-Wet after running(idle to med speed, repeated) for 1 min.

Erik
 
Hmm, never considered too much fuel. What happens with yours if you hold it wide open? Mine bogs down after a second or two. Both my adjustment screws are at one full turn open.
 
Opened up the muffler and it's all clear, it's basically a metal can with a screen over it so I'm not sure what would clog it up anyway.
I'm about out of ideas, might have to break down and take it to the dealer :-S The piston looks really clean and I don't think the saw has seen that much use, maybe junk in the carb has something plugged?
 
sounds like a good carb cleaning is in order. Not that tough to do, and a skill you will use often in the future.
get the baseline stuff right first. carb clean, fuel lines, filter, plugs, and compression. sounds like you are almost there.

k
 
Yeah, probably, I'm just getting annoyed with this thing and want to cut something with it, not work on it. I've done a number of carb rebuilds in the past, some were even successful ;-) nothing this small though. I'm going to check the tank vent and the impulse hose first.
 
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