Chainsaw carb adjustment issues

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drummer4468

Pre-takeoff checklist
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drummer4468
Hi all, hoping someone with two-stroke experience can help me out. I recently picked up a used Stihl 026 chainsaw and this carb has been giving me problems since day one.

Guy I bought it from rebuilds Stihls and Huskys, and said the only thing he hadn't gone over/refurbished was the carb. Everything else was mint, no cylinder scoring, etc. When I first ran it, it started spewing fuel. Quickly found out the fuel pump cover had an odd chip in the side, so he replaced it for free and solved that issue(may or may not be relevant). Put the carb back in, adjusted the H and L jets to about 1 to 1-1/4 turns out(it's got a ported exhaust so a little more than the standard 1 turn). Got it started up and adjusted them accordingly, slightly ROP at both idle and WOT accordingly. Runs incredibly well and responsively with plenty of power.

The problem I'm having is that she HATES cold starts. Even yanking away at full choke, I can never get it to kick over until I manually prime it by dribbling some fuel down into the carb(no primer bulb). Then it fires right up and runs great. Which tells me it's getting good spark, just not pulling enough fuel. It cranks right up when it's warm though, such as when stopping to fill the tanks, long as I don't let it fully cool.

Any ideas on what the issue could be? The fuel line looks good and tank is full. Checked to make sure it wasn't under vacuum. The impulse line looks good as far as I can see, though it's a PITA to fully access without tearing the entire powerhead apart. Hoping someone can tell me I'm missing something obvious, or at least point me in the right direction. Never had this much of an issue with starting on an otherwise good-running engine.
 
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Brainstorming note: I have a brand-new spare chinese carb I can toss on it if there are no other glaring issues. Only other things I can think of is maybe a leak in the choke(which is just a flapper integrated into the air filter for some reason). Beyond that, maybe timing is outta whack? I dunno, just kinda spitballing while sitting here at work.
 
Bad fuel pump diaphragm possibly, or leaky check valve(s). Get a carb rebuild kit, or a new carb.
 
Did you check the fuel line? My infrequently used saw used to need a new fuel line frequently from ethanol destruction.
 
Check the crank seals as well as the impulse line. The fuel pump runs from the crank case impulse. If you have a leak, it will not pump fuel at low RPM.
 
Rebuild on a crappy little 2-stroke carb? Surely you jest. You can buy a whole new carb for less than $10 usually. Stay away from ethanol-laden gas once you replace it.
 
drummer4468 said:
Any ideas on what the issue could be?
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Some Stihl products require a set procedure to start when cold. On my 025, which is similar to the 026, if all else appears good and it runs, move the control lever at the LH side of the handle all the way down and lock the trigger open. Pull on it until it pops once then move the control lever up ONE click. It should start within 5 pulls depending on OAT.

FYI: be careful with the $10 Ebay carbs. I usually buy carbs, etc. from Jack'ssmallengines, firedog.com, or a dealer, especially for Stihl, or any other like place with a good return policy. Have a pile of new Chinese carbs that weren't manufactured properly and it cost more to return than worth.
 
My Stihl 028 can be cantankerous when cold. Once I get it running, though, it's great.
 
Not getting enough fuel with the choke on is different from anything I have. Most of the saws I own or use at the Fire Department more than one pull full choke floods them. Some you don't even use choke or it will flood.
 
Should've bought an Echo . . . :) I'd just buy a new carb from a reputable source rather than trying to rebuild it.
 
flyingron said:
Rebuild on a crappy little 2-stroke carb? Surely you jest. You can buy a whole new carb for less than $10 usually. Stay away from ethanol-laden gas once you replace it.
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That's been my SOP as well. I've been replacing carbs on small engines the past couple years. Never had problems before, but lately I have been. $10 for a brand new carb from Amazon, usually less. 5-10 minutes on, start it up, usually runs better than the factory carb did because the new carb isn't calibrated for crappy EPA settings.
 
My Stihl weed eater had carb problems. After I checked the s/n and realized it was over 10 years old I didn’t feel so bad. I couldn’t find a rebuild kit so I bought an OEM replacement and it ran like new. I was suspecting something in the fuel pump or filter screen was keeping things too lean. I cleaned what I could without disassembly, but never could get it right. Whatever it was it went away with about 10 minutes and a screwdriver.
 
I'll third the just buy a new carb on amazon method, it's worked for me.

Of course, lately my problem seems to be chainsaws dying under load and not restarting after they warm up. *sigh* step one of any chore is repairing the tools it seems.
 
Stihl weedeaters, many
new OEM or online carbs
fresh fuel
The H and L needles have a specific position on mine, I think the local repair woman told me, I wrote on a sheet pinned to garage wall.
Not enough fuel for me was always plugged passages or defective prime bulb
 
it needs a reed valve.
 
Before replacing the carb I would take it off and immerse in Pinesol for two days. Rinse with water, dry and reinstall.
 
swingwing said:
Before replacing the carb I would take it off and immerse in Pinesol for two days. Rinse with water, dry and reinstall.
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I tried various things to get my wife's heavy duty leaf blower back to life. Even completely disassembling it and soaking it in solvent didn't help.
 
How much is the muffler modded? Too big of a hole or a hole in the wrong location and you loose the back pressure needed to get it to run right.
 
Let'sgoflying! said:
Stihl weedeaters, many
new OEM or online carbs
fresh fuel
The H and L needles have a specific position on mine, I think the local repair woman told me, I wrote on a sheet pinned to garage wall.
Not enough fuel for me was always plugged passages or defective prime bulb
Click to expand...
I do know the primer bulb had failed (age-related disintegration), but the carb had problems prior to that. I checked on a replacement primer bulb, but could only find aftermarket 3-packs of various sizes and then hope one would fit. Turns out buying the whole carb, with a primer bulb included, was nearly the same price as the bulb itself. Made for an easy decision -- except that the gasket between the carb and the engine seems to never be included.

I can't remember if mind has the factory set H/L or if I removed the limiter so I can adjust it, or what. Either way, it works better than it has in years.
 
Wow, thanks for all the replies. still scratching my head but more confident I'm not missing something painfully dumb. I'll get 'er figgered out eventually.

Dana said:
Bad fuel pump diaphragm possibly, or leaky check valve(s). Get a carb rebuild kit, or a new carb.
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Diaphragm, screens, and gaskets all looked good to me. I'll try just replacing the carb and see if that helps.

Hang 4 said:
Did you check the fuel line? My infrequently used saw used to need a new fuel line frequently from ethanol destruction.
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Yep, fuel line looks good to me. may replace it as I have a spare anyhow. I stay far away from ethanol, usually use the overpriced premix for shelf stability. I don't run the saw often enough to mix gallons at a time anyways.

Joe_B1 said:
Check the crank seals as well as the impulse line. The fuel pump runs from the crank case impulse. If you have a leak, it will not pump fuel at low RPM.
Click to expand...

That's one thing i was worried about. if tossing my spare carb on there doesnt work, i'll tear it further apart and inspect all that.

flyingron said:
Rebuild on a crappy little 2-stroke carb? Surely you jest. You can buy a whole new carb for less than $10 usually. Stay away from ethanol-laden gas once you replace it.
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Yeah, i already have a new $15 carb on standby, just wanted to rule out adjustment errors. And I stay far away from ethanol as stated above.

Zeldman said:
Try fuel without alcohol.
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See above

Ted said:
That's been my SOP as well. I've been replacing carbs on small engines the past couple years. Never had problems before, but lately I have been. $10 for a brand new carb from Amazon, usually less. 5-10 minutes on, start it up, usually runs better than the factory carb did because the new carb isn't calibrated for crappy EPA settings.
Click to expand...

Agreed, carbs are crazy cheap to get on amazon. I just wanted to stick to the OEM one if at all possible.

Tom-D said:
it needs a reed valve.
Click to expand...

Now this is something I hadn't thought of. I'll have to look into it. thanks.
 
I take my generator on the wagon/trailer attached to the Z-turn and traverse the property and my chainsaw never fails to start. If you need a regular duty home unit consider something like this: https://www.amazon.com/dp/B00YFTA84U?tag=jchainsaw-20

Battery powered are also available but they just don't have enough oomph to do the job ...
 
I have also thought my next gas chain saw will be an Echo brand. But I opted for a light weight Ryobi 18V unit for limbing. I have two big Stihls and one of them is a cold blooded mother. Not as bad if I replace the spark plug every 10 to 20 hours of use. The other larger one is pretty good about starting but I don't like the weight anymore with a 20" bar.
 
I never have these problems with my electric chainsaw from Montgomery Wards....
 
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