My 026 Running Issues...possible air leak?

[12guns]

Well, my 026 is acting up now. I ran it yesterday for several hours of clearing some massive pine trees. It ran good for a while, then sputtered out and died. I filled the gas tank up and was able to cut for another few mins before it died again. Initially I thought the fuel filter was out of the gas, but that was not the case.
It sounded almost like an electrical "cut out" at one point, so I check the wires under the lid. The yellow wire was worn through from rubbing on something. I taped it up and made sure it was not under pressure. Still cutting out.
Then at one point I could point the saw up and keep it running, which would indicate a fuel problem, right? The "H" jet still adjusts fine, so I"m hoping it's not a crank case seal like on my friends saw.
Oh, and I could hear an air leak on the top left of the fuel tank next to the black plastic thing w/ a screw in the top (no idea what that is). So could my air leak cause these issues when pressure builds up in the tank? I'll admit my saw got slammed to the ground when one large pine broke free...Thanks for any help. Need to get this thing running right and I haven't had to take it to the shop before, don't really want to start now.

 

[dswensen]

The black plastic thing with a screw in it is the fuel tank vent. Sounds like it's doing it's job.

 

[spudulike]

The very first sign of an air leak is usually a wandering idle - usually an increase in idle speed.

When the leak gets worse, the saw will race like it is running out of fuel and often won't rev cleanly in the mid range, it will make that Whoom Whoom sound when the throttle is opened - like a cold 345,346,350 Husky.

I would check the piston by removing the muffler and looking at the piston and then get the saw pressure checked - it could be a blocked breather - just loosen the fuel cap and se if it clears the problem. The sound you are hearing may be the air coming in to the fuel tank.

 

[12guns]

Thanks for the replies. It seems to idle ok, just runs for a little bit, then bogs down and dies suddenly when I get on the throttle. The leak that I heard was coming from the bottom of the black gas tank lid, but was a very small leak, so if that's the vent, I guess it's ok. I have not done any work to the carb in 8 or so years, maybe time for a carb kit? I'll take it all apart today and see if I find anything out of the norm. I did notice that at one point it would stay running, but only at about half throttle, then would crap out again.
If I don't find anything today, I'll have the case pressure checked this week sometime. Any other things to check?

 

[12guns]

The very first sign of an air leak is usually a wandering idle - usually an increase in idle speed.

When the leak gets worse, the saw will race like it is running out of fuel and often won't rev cleanly in the mid range, it will make that Whoom Whoom sound when the throttle is opened - like a cold 345,346,350 Husky.

I would check the piston by removing the muffler and looking at the piston and then get the saw pressure checked - it could be a blocked breather - just loosen the fuel cap and se if it clears the problem. The sound you are hearing may be the air coming in to the fuel tank.

Where is the breather located? Same as the fuel tank vent? It has tons of compression, but I'll check the piston today (although I don't really know what a normal vs. scored piston looks like)

 

[spudulike]

Where is the breather located? Same as the fuel tank vent? It has tons of compression, but I'll check the piston today (although I don't really know what a normal vs. scored piston looks like)

Tank vent/breather - same thing - usually just behing the choke lever and looks like a black mushroom but does come in different versions.
The symptoms you have are a blocked breather, dirt in the gauze filter in the pumping part of the carb or holed impulse/fuel line.

All would have similar results

 

[12guns]

Great info, thanks.
I have the carb off and fuel line/filter out and off. The fuel line broke when I pulled on it, so I'm sure it's time for a new one. I'll get a carb kit Monday along w/ a new fuel line.
Next question: What is the yellow wire for going to the switch area? Black seems to be ground. The yellow is worn over half way through from being pinched at some point. I'll patch it up while I'm in there, but just wondered if that could cause it to run poorly? I wouldn't think so, but didn't know. Thanks

 

[ttyR2]

Need two wires for the ground to work as the saw body is plastic. One wire is from the low-voltage side of the coil, the other is back to a ground point. Short together and the engine dies.

 

[blsnelling]

Does not sound like an air leak at all.

 

[12guns]

I wraped the torn yellow wire to insulate from the black wire. No shorting, but even then was still running poorly. Looks like a fuel problem. Hope the carb kit and new fuel line fixes it!

 

[spudulike]

I wraped the torn yellow wire to insulate from the black wire. No shorting, but even then was still running poorly. Looks like a fuel problem. Hope the carb kit and new fuel line fixes it!

Just make sure you get the order of the gaskets in correctly, the diaphragm spacer gasket goes between the carb body and the diaphragm, the gasket with the two semi circular flaps on it goes against the carb body with the other gasket on top of it - worth taking a few digital images on stripping it down before you take the old gaskets off!

I have seen quite a few bad carb rebuilds in my time!

 

[Mad Professor]

Check that the carb diaphragm cover is not full of sawdust. Won't pump any fuel if it is.

P.S. regular or intellicarb?

 

[DG2244]

I also believe you have a metering problem. The giveaway is when you tip the saw up and it runs better. As pointed out already, could be debris between the cover and the metering diaphragm. Makes sense that if you are spending time pulling the carburetor, a new kit should go in.

 

[12guns]

problem solved

After cleaning the carb real good and replacing the fuel lines and filter, I saw an arc between the spark plug wire and the metal part of the rubber cushion. Looks like when I turned the saw up, the wire pulled back enough that it would not arc. I taped up the wire for now, will replace soon. Thanks for all the help! Seems to run fine now!