Trouble with an 026

[fin460]

I have an 026 that races at idle and won't tune out. It was a complete rebuild, split, new bearings seals. I haven't replaced the rubber parts, but have a impulse line and fuel line, filter on order.

It is passing multiple pressure and vac tests, cold and warm, and I've turned the crank over while testing.

Cylinder is always hot, after I make a couple short cuts, trying to get it to tune.

I plug my mittyvac into the impulse line, and cap off the muffler and the end of intake boot.

I had a Chinese style wt194 and tried it in place of the original 194. saw acts the same.

When I hold the throttle down it will rev up slow sounding super rich then all of a sudden, something lets loose and it rapps out super lean super fast.

Any ideas, i'm anxious to try a new impulse line, but the old one passes pressure test.

 

[Duane(Pa)]

Have you tried running it without the air filter installed?

 

[fearofpavement]

Well, it appears it's getting air "somewhere" so I would be suspicious of the fuel line and the carb intake boot. (clamps tight?)
The impulse line can cause a saw to not run but probably not the source of a lean condition. Do you have another similar model saw you can trade some parts around on?

 

[fearofpavement]

Just to mention, I had an 026 with a similar problem and it was a cracked fuel line.

 

[fearofpavement]

Pull the fuel filter out of the tank, pull the filter and pressurize the fuel hose and carb. Should hold 8 to 10psi. That will identify a defective fuel line.

 

[fin460]

ok, I'll check the fuel line while i'm waiting on the new one.

 

[Fish]

Also make sure the old fuel line is not overly soft from age/etc., it can work fine then collapse while running....

 

[Mastermind]

I'd be looking at the fuel line as well. They are bad to crack on that model.

 

[fin460]

Have you tried running it without the air filter installed?

I think so, but that might have been another saw, Why?

 

[Fish]

When pulling the line/filter out of the tank, note how it feels, also may feel gummy/sticky.

 

[Duane(Pa)]

I think so, but that might have been another saw, Why?

Choke flap is a colossal pain in the ... On this model

 

[fin460]

okay, long story short, I replaced the fuel line, and ran fine until the second or third cut, then ran away again, wasn't able to get a handle on the tuning.

I repressure tested again while warm, and found no leaks, tested again and had a slow leak, thought it was coming from the manifold. So I pulled the cylinder, found nothing wrong, then pulled the flywheel to check the seal on that side again, and noticed the coil and flywheel magnet in full contact, no gap.

flywheel has a light rub mark from the coil. could this be my issue,

 

[fossil]

I had a very similar issue with a Poulan 2800. It held pressure and vacuum better than any saw I've tested. The leak was between the carb and the boot. Changed the boot out and it is OK now. I still can't see anything wrong with the boot I changed out.

 

[BuckthornBonnie]

okay, long story short, I replaced the fuel line, and ran fine until the second or third cut, then ran away again, wasn't able to get a handle on the tuning.

I repressure tested again while warm, and found no leaks, tested again and had a slow leak, thought it was coming from the manifold. So I pulled the cylinder, found nothing wrong, then pulled the flywheel to check the seal on that side again, and noticed the coil and flywheel magnet in full contact, no gap.

flywheel has a light rub mark from the coil. could this be my issue,

An improper gap would cause running/starting issues, but I'm not sure it would cause your specific symptom. Is the bearing seated correctly (just bottoms out in case, so I'm assuming). Crank scratched from removing old seal? How's the coil... mount up ok?

 

[fin460]

What does no coil gap cause? Improper spark? early or late spark? The saw seems like it would run stupid rich for awhile, then take off finally at full throttle.

Tonight I noticed it would run stupid rich on its way up to full throttle then start loading up and die with the throttle fully engaged.....

I need some lessons for sure.

On the carb I've basically ran the low setting from 3/4 to 1 1/4 sometimes it seems to respond normally, lean out, or load up, then other times seems like the air leak is active and I can't keep it running long enough to get an idea.

the high setting is usually pig rich , or has no affect, I just can't get the saw to run normal long enough to get a good feel on the tune settings.

I had a very similar issue with a Poulan 2800. It held pressure and vacuum better than any saw I've tested. The leak was between the carb and the boot. Changed the boot out and it is OK now. I still can't see anything wrong with the boot I changed out.

I wonder the same thing, I pressure test at the back of the intake boot, using my thumb as a block off, I spray my thumb and make sure it isn't leaking.

the intake boot looks fine, but I can't see how it mounts up with the insert ring and the carb bolted off. I may try and grease it or use some sealent there.

I may and try a different ring off of another 026 and see if it is the same shape as the one this saw has.

I just need more time with it, I am super frustrated, but am excited to learn something from this saw. It has been the one I can't figure out.

 

[fin460]

An improper gap would cause running/starting issues, but I'm not sure it would cause your specific symptom. Is the bearing seated correctly (just bottoms out in case, so I'm assuming). Crank scratched from removing old seal? How's the coil... mount up ok?

I may or may not have the bearings and seals in the right place, I replaced them myself, but I wasn't for sure how far to put the seals in. Its probably been a year since I split the case and installed the new bearings and seals. It has no run time since then either. I couldn't figure it out then, and now I'm revisiting the saw and its problems.

 

[drf256]

Gotta think a bit more on this, but check that the coil hit didn't shear the key.

May wanna try a different flywheel and coil as well. I saw a flywheel magnet go bad once from the polarity changing from a hit.

 

[MustangMike]

Is the flywheel hitting the coil because the bearing is no good, which would also cause the seal to leak while running?

A lack of gap would advance your timing. Most set the gap with a business card, very scientific!

 

[jmssaws]

I say airleak and it seems everytime I have a saw with a airleak it's where the carb and boot meet or the flywheel side seal.

 

[Chainsaw Jim]

That carb and boot match up is almost always a problem with older boots.