026 problems

[Brian13]

I have been working on a 026 for a friend of my dads, and have run into a problem. It looked like the saw had sat for a long time, the fuel line had melted to the top of the fuel tank, it was missing the tank vent, and the carb needed a good rebuilding. It passed a vac test and it had good compression with no scoring. So I cleaned the jellied fuel line out of the tank, got a new fuel line, vent and carb kit. When I went to test it today, it will start up idle fine, but as when I put it into wood it will start to sound like its missing, bog down and want to die. It would cut like it should for a second or two and then just loose all power. When I got the tank vent the guy behind the counter was not real sure on weather or not I was getting the right vent. The IPL shows one thing but what I was describing to him he thought it needed the hose with grub screws. So I am thinking it is either the tank vent, or there is still some crud in the carb that needs to be cleaned. Does it sound like I am on the right track? Here is a pic of the tank vent as well.

 

[1steve]

Brian i think your on the right track, tank vent you need is part# 1121 350 5800. Hope this helps.

 

[Brian13]

I was thinking that was the vent I needed. The tank vent is what I am hoping the problem is, being as the guy at the shop wasnt sure what vent I needed and I had a feeling it wasnt the right one.

 

[Brushwacker]

Did you vac + pressure test the crankcase ?
My guess would be a bad seal or an problem with the ignition from what you discribe. If you had a good known module you could try I'd do that and then the pressure -vac test if needed. It looks to me that vent should work.

 

[Brian13]

I did the vac test and it passed just fine. The only thing that keeps me from thinking its an air leak is its not racing. When it will run no load WOT the rpms are stable. I will do a vac test again tomorrow just to rule that out though. The one thing that was bothering me about the vent, is when I was testing it out before I took it out to cut, it looked like fuel was trying to bubble out the vent. Never watched the vent before to see what it was supposed to do, but it looked kind of funny to me.

 

[Andyshine77]

Sounds electrical. Check all connections and replace the spark plug. I've had this happen to me more than once, and every time it was a crappy Champion plug. Every Champion spark plug I've used has failed.

 

[Pendagator]

I've been working on an 026 too and I'm not so sure about my tank vent either. Your tank vent doesn't look like the one's in the IPL's. Check out this thread http://www.arboristsite.com/chainsaw/45911.htm That thread shows an IPL ( upside down). The vent it takes depends on when the saw was made. I thought about using a clear hose like you have, stuffing some air filter foam in it for a filter, and then adding the 1110 353 1600 "tit" they talk about in that thread. I don't know if that would work or not.

 

[Brian13]

Sounds electrical. Check all connections and replace the spark plug. I've had this happen to me more than once, and every time it was a crappy Champion plug. Every Champion spark plug I've used has failed.

My dad suggested electrical as well, so I will check all connections, and replace the plug. I reused the plug that was in there because when I tested for spark I was getting spark. It would be nice if a new spark plug fixed the problem LOL.

I've been working on an 026 too and I'm not so sure about my tank vent either. Your tank vent doesn't look like the one's in the IPL's. Check out this thread http://www.arboristsite.com/chainsaw/45911.htm That thread shows an IPL ( upside down). The vent it takes depends on when the saw was made. I thought about using a clear hose like you have, stuffing some air filter foam in it for a filter, and then adding the 1110 353 1600 "tit" they talk about in that thread. I don't know if that would work or not.

I have another vent like the one in the IPL on the way. I will see what that does for it, it wasnt that expensive. I went with the 5800 PN, so I will see what happens.

 

[striperswaper]

impulse line?

 

[Brian13]

I just did a compression test, came out to 165psi, I am doing a vac test now, and so far so good. And a tried a different spark plug that I new was good, and the low end rpms fluctuate about 400-500 rpms, but high end still seems stable. So right now I am thinking its either the vent, carb is still dirty, or the coil is going bad. I am hoping it is one of the first two. The guy I am doing this for want to get it running for as little money as possible.

 

[Stihl-in-Ky]

I bought an o26 that did the same thing and it was the spark plug wire was partly abraided by the metal that holds the antivibe rubber in beside the plug wire? :msp_blushing: I found it by running it at night and could see it jumping spark to ground.

 

[Mad Professor]

Loosen the gas cap and see if it runs WOT on the right side (e.g. clutch side down so you don't spill fuel. If it does, problem is the vent, if not.............

 

[Brian13]

Doing good on the vac test, hasnt dropped at all. I did pull the carb to clean it again and noticed that I flip floped the metering diaphragm and gasket. Wonder if that would cause the symptoms? I am sure it dosnt help LOL. That was my fault though. Getting ready to put it back together and start it up. Will check the plug wire before I get it all back together too.

 

[Brian13]

:bang::bang::bang::bang::bang::bang: Well it looks like I am causing more problems then I am curing!! I put the carb back together like the IPL shows, carb body, gasket, metering diaphragm, and cover. And it ran worse, didnt want to run at all. Thinking the metering lever isnt set right? What should it be set to? I also managed to smash the ground wire, and mangle it, so I think I am done for the day before I break something else.

 

[pioneerguy600]

Sounds like you are having fun with this one.
A tank vent is just a tank vent, no matter what you use, all it does is let air in the tank to make up for fuel removed. Oldschool vents allowed air in or out of the tank, newer EPA regs required vents to only let air in, no fuel vapours out. A piece of tubing with a grub screw will work fine as far as your engune is concerned.
Metering lever height is crucial to good engine performance, what carb do you have on that saw?
Any electrical problem will affect engine RPM so it all has to check out good, it is possible the module is going bad but they usually will quit working when they get hot, after running hard for 10-15 mins. They loose spark when hot but will produce spark again once cool, triggering unit failing.
Hope you get it sorted out.

 

[Brian13]

Thanks Jerry, that rules out the tank vent. And I think that rules out the coil, at least 75% chance its not the coil. Right not I am leaning towards the carb. Its a Walbro WT194. I reused the metering lever, so I didnt mess with it as far as adjusting it. After I put the metering diaphragm and gasket in the right order, it would only run on the high idle setting and start to race like it was running out of fuel and would not run for more than a second off of the high idle and throttling up would not help. It would bog down as soon as you hit the throttle and die out completely. So right now I am thinking that the metering lever needs to be raised some. Just not sure where it needs to be set at. Once I get that settled I can see what it does as far as the coil is concerned.

 

[pioneerguy600]

Thanks Jerry, that rules out the tank vent. And I think that rules out the coil, at least 75% chance its not the coil. Right not I am leaning towards the carb. Its a Walbro WT194. I reused the metering lever, so I didnt mess with it as far as adjusting it. After I put the metering diaphragm and gasket in the right order, it would only run on the high idle setting and start to race like it was running out of fuel and would not run for more than a second off of the high idle and throttling up would not help. It would bog down as soon as you hit the throttle and die out completely. So right now I am thinking that the metering lever needs to be raised some. Just not sure where it needs to be set at. Once I get that settled I can see what it does as far as the coil is concerned.

The WT series carb requires a special Walbro guage to set it correctly, tool number 500-13, its shaped like a W and has three separate setting levels for all the Walbro carb models. Before I had one of these gauges I used to set the metering lever around .030 below the carb body casting, it worked but the tool seems to make them work better. I must actually measure the distance the tool sets the lever to to know for future posts to members that don`t have that tool, it only costs about $5. so its worth having.
The problem does sound fuel related so hope you get it sorted out.

 

[Andyshine77]

The 026's are known to have carb issues, I've seen it a few times. Anyway it sounds like the carb, you may need a new one, sometimes they can't be fixed.

 

[pioneerguy600]

The 194 I have found to be the better of the lot of carbs used on the 026 saws but you are right, once in a while a bad one comes along that just won`t work right. I had one myself and under high magnification looking in the low speed adjust bore I could see the seat was spread and disfigured, likely by either the wrong shaped speed needle or just being seated too hard. I have also seen three carbs with one of the adjuster needles broken off from being turned in way too hard, whats up with that?

 

[THALL10326]

Doing good on the vac test, hasnt dropped at all. I did pull the carb to clean it again and noticed that I flip floped the metering diaphragm and gasket. Wonder if that would cause the symptoms? I am sure it dosnt help LOL. That was my fault though. Getting ready to put it back together and start it up. Will check the plug wire before I get it all back together too.

Passing the vac test doesn't rule out a crankcase leak. You need to do a pressure test as well. Hardened seals will pass a vac test but fail a pressure test miserably. Recently did a 028 that passed a vac test but failed bigtime under pressure. Clutch side seal was leaking bigtime under pressure but held fine under vac. This saw would idle but race and then die under a load. Replaced the seals, saw now runs perfecto. Do a pressure test to rule out a crankcase leak and go from there. If you find no leak then proceed on..