026 Grief

[GCTS]

I've got an 026 that has sat for a couple years and have been having a hard time getting it running. It had sat with fuel in it, possibly with ethanol, and ran for a bit at first then got slower and slower and eventually wouldn't start. I cleaned out the tank, replaced the fuel line and fuel filter and ran some fresh mix with sea foam. I was able to get it to start with a huge cloud of white smoke when putting sea foam right into the carb, but then it would die out. I cleaned out the carb and put in a carb kit (Walbro WT194A) and had meant to change the impulse line too but the dealer gave me the wrong part, so I put the old one back in (it looked okay, but maybe it had holes I couldn't see?). The carb actually looked okay to my totally untrained eyes, except the screen (strainer?) was gummed up with what looked like wet clay - which I imagine was gunk from the sea foam?

I then took it out and ran it for a couple minutes and it seemed to run fine, but then stalled when it got back down to idle. Now it starts easily but will stall after 10 or so seconds at idle now matter how high I turn up the LA screw. I can keep it running as long as I don't let go of the throttle for more than a few seconds, but even at full throttle it feels like it's only at about 60% power.

Any ideas what to check next?

• The air filter looks okay - it could probably stand replacing but doesn't look so bad that it would be causing this to me. (BTW, I just washed it out with soap and water but wondering if that was a bad idea. Should I give it a couple days to totally dry so I don't risk getting water droplets in the carb?)
• Just put a new spark plug in but it didn't change anything
• Took the muffler off and looked at the piston and it looks like new to me.
• The Walbro carb kit had a diaphragm and diaphragm gasket that were a slightly different shape than the ones that were originally on - but they seemed to fit good, so I don't think that was an issue. I think they were made so that they would fit other carbs as well as this one...

Edited to add:

• I checked the fuel tank vent and it looked okay to me, though I'm not sure exactly what I should be looking for.
• After the carb kit, I reset the low and high screws to 1 full turn (as per the sticker on the saw)

Thanks in advance for any help

 

[PV Hiker]

The carb actually looked okay to my totally untrained eyes, except the screen (strainer?) was gummed up with what looked like wet clay

The Walbro carb kit had a diaphragm and diaphragm gasket that were a slightly different shape than the ones that were originally on

Looks like you included lots of detail in your assessment. You still have a carb issue. The clay stuff was the ethanol fuel combined with moisture gummed up. You still have most likely this stuff in your carb passage ways and giving you grief.

Also the carb kit parts should match exactly what was is in the carb. the needle seat arm needs to be adjusted to specs. I think there is more to do to get all the carb passage ways cleaned out.

 

[GCTS]

Here's a pic to show the carb kit discrepancies... I think the parts that were different sit on the outside of the carb (top edge). Original parts on the top and ones I put in on the bottom. I did flush out the carb really thoroughly with carb cleaner after I took it apart then blew it clean & dry with a compressor at 25 psi. I felt like I was being a bit excessive with the flushing - I used about 1/3 bottle of GumOut and really worked on getting it to blast through all the passage ways... The only thing I didn't do was change out the welch plugs. Could that likely be the issue?

 

[a. palmer jr.]

Many people on here will disagree with me but if it were mine I'd try ordering a new carb online (don't know if I can say where) and try it. They're only around 15 bucks but they've always worked for me. You could also check the muffler since you said it sat for awhile, maybe something built a nest in it...

 

[Bob Hedgecutter]

Clean and flush out the fuel tank and clean out the fuel filter.
But I am more prone to think you might also have an air leak problem.

 

[GCTS]

Thanks - I already did clean and flush out the fuel tank and put a new fuel filter on... Also took the muffler off and it wasn't bad (and no scoring on the piston). Where would I start looking to rule out an air leak?

 

[Bob Hedgecutter]

Thanks - I already did clean and flush out the fuel tank and put a new fuel filter on... Also took the muffler off and it wasn't bad (and no scoring on the piston). Where would I start looking to rule out an air leak?

Ideally, you would pressure and vacuum test the powerhead and find the leak that way (if indeed there is one and it is not just all a carb problem).
But you can visually inspect carb manifolds, fuel lines and impulse lines. With the saw running you can get someone to spray likely spots like the crank bearing oil seals with brake cleaner and see if the saw stumbles or even stops.
A saw that does not want to idle, wont idle with the LA screwed all the way in , but runs at full throttle USUALLY is a pretty good indicator for an air leak and if you try to tune it away, you may very well burn the topend up.
You could take the saw to a dealer and ask them to do a pressure and vacuum test on it for peace of mind- but it will be an added cost.

 

[Mr. Chips]

I've got an 026 that has sat for a couple years and have been having a hard time getting it running. It had sat with fuel in it, possibly with ethanol, and ran for a bit at first then got slower and slower and eventually wouldn't start. I cleaned out the tank, replaced the fuel line and fuel filter and ran some fresh mix with sea foam. I was able to get it to start with a huge cloud of white smoke when putting sea foam right into the carb, but then it would die out. I cleaned out the carb and put in a carb kit (Walbro WT194A) and had meant to change the impulse line too but the dealer gave me the wrong part, so I put the old one back in (it looked okay, but maybe it had holes I couldn't see?). The carb actually looked okay to my totally untrained eyes, except the screen (strainer?) was gummed up with what looked like wet clay - which I imagine was gunk from the sea foam?

I then took it out and ran it for a couple minutes and it seemed to run fine, but then stalled when it got back down to idle. Now it starts easily but will stall after 10 or so seconds at idle now matter how high I turn up the LA screw. I can keep it running as long as I don't let go of the throttle for more than a few seconds, but even at full throttle it feels like it's only at about 60% power.

Any ideas what to check next?

• The air filter looks okay - it could probably stand replacing but doesn't look so bad that it would be causing this to me. (BTW, I just washed it out with soap and water but wondering if that was a bad idea. Should I give it a couple days to totally dry so I don't risk getting water droplets in the carb?)
• Just put a new spark plug in but it didn't change anything
• Took the muffler off and looked at the piston and it looks like new to me.
• The Walbro carb kit had a diaphragm and diaphragm gasket that were a slightly different shape than the ones that were originally on - but they seemed to fit good, so I don't think that was an issue. I think they were made so that they would fit other carbs as well as this one...

Edited to add:

• I checked the fuel tank vent and it looked okay to me, though I'm not sure exactly what I should be looking for.
• After the carb kit, I reset the low and high screws to 1 full turn (as per the sticker on the saw)

Thanks in advance for any help

I had a similar situation with an 026 several days ago. I opened up the H and L screws three turns and kept it running as long as I could. When it died, I pulled the plug, cleaned it with a propane torch, and pulled the engine over a few times. I replaced the plug, returned the screws to the default setting, and the saw started and ran well. I ran a tank of fuel through it and it cut great, but I had to tweak the low end a few times to keep it running at idle. It finally settled down.

I didn't think of the screw idea myself, someone on this site suggested it. I don't remember who, but I owe him a thank-you.

 

[a. palmer jr.]

If you think you may have an air leak you can make a kit yourself to check it. I made my own with a few small air hoses, a gauge and a blood pressure tester bulb and a few T fittings. You just have to pump it up to about 5-7 lbs. You'll have to block off the intake (used a cork for this, with carb removed), stick a piece of inner tube rubber behind the muffler, hook the hose to the pulse line and you're ready to go...

 

[Vintage Engine Repairs]

Can you upload a video?

 

[Overlooker]

Where would I start looking to rule out an air leak?

If you are only planning to fix this one saw, find a service technician to pressure/vacuum test it. If you plan to diagnose and fix other saws, look into acquiring your own test equipment. I found that the hand-operated vacuum pump that I had for bleeding brakes was easily adapted for the task. Pressure/vacuum testing has helped me find leaking oil seals, bad cylinder gaskets, and, equally important, it has kept me from replacing parts that didn't need replacing. I use the same test equipment every time I work on a carb. Watch Leon's videos for more info. O (aka T-A)

 

[Vintage Engine Repairs]

If you are only planning to fix this one saw, find a service technician to pressure/vacuum test it. If you plan to diagnose and fix other saws, look into acquiring your own test equipment. I found that the hand-operated vacuum pump that I had for bleeding brakes was easily adapted for the task. Pressure/vacuum testing has helped me find leaking oil seals, bad cylinder gaskets, and, equally important, it has kept me from replacing parts that didn't need replacing. I use the same test equipment every time I work on a carb. Watch Leon's videos for more info. O (aka T-A)

One of the most important a 2 stroke rebuilder can own! I test all my lines / hoses, seals, carbs, gaskets, manifolds, filters, tank vents and more using one.

 

[a. palmer jr.]

Yes, there's several videos online concerning testing for leaks, better than any video I could make. I actually have never made a video and don't think I have the equipment for it. Leon's is a good place to start.

 

[John Lyngdal]

The old diaphragm has ethanol damage as you suspected and the gasket differences shouldn't be an issue.
Stihl OEM carbs and the aftermarket replacements are both made in China. If you can't get it running after rebuilding the carburetor, I'd hop over to eBay and purchase a AM unit.

 

[GCTS]

Thanks for the replies everyone - this site is awesome.

I ordered a pressure/vacuum test kit. While I'm waiting for it to arrive, I just pulled the carb out again to maybe fire some cleaner through it again in case I missed something the first time.

Question: When blasting the carb cleaner through the passageways, should I first remove the H & L screws? I'm wondering if there are some passages to the screws that maybe didn't get cleaned the first time around? I wasn't sure whether the could/should be removed when I cleaned it the first time.

Here are some pics of the carb (after cleaning out and installing the carb kit the first time) in case there is something obvious that is wrong with it.

If it doesn't work out when I clean and put it back together and if the pressure & vacuum tests go okay, I'll try ordering an aftermarket carb - I suppose that's the next logical step?

Thanks again for all your help!

 

[Maintenance supervisor]

Does the plastic nipple on the carb spin with little effort? Dont force it if it doesn't, but that connector can be a fuel leak also that can be a bugger to diagnose.

 

[GCTS]

The white one for the fuel line? It feels solid. One thing I was wondering about though, is when I mount the carb, the brass nipple that fits into the impulse line feels like it goes in with very little resistance. I didn't replace the impulse line amd, while it looks to be in ok shape, wondering if the rubber stretched out a bit and might let some air in there?

 

[Maintenance supervisor]

Yes the white one, and if the impulse line is loose you'll be starving for fuel.

 

[GCTS]

Ah - thanks.. I suppose in that case it would make sense to order in a new impulse line and see if that fixes it before sinking more money into a new carb?

I'd ordered one along with the carb kit, but they gave me 2 fuel lines instead and the old one looked good after I'd pulled it so I put it back in, but now thinking the fit to the carb should be tighter.

 

[a. palmer jr.]

In answer to your question: I always take both the H and L screws out of the carburetor when cleaning it..be sure and mark them so you'll know which one is which...