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Post by herbertv2 on Apr 23, 2015 23:18:33 GMT -5
I aquired a Homelite XL 925 from my dad, that was originally my grandfathers. My dad gave up trying to get the old girl running right, he rebuilt the carb cleaned the fuel tank and replaced the fuel lines. He was able to get it running again but not right and after messing with it for a while gave up on it and bought a new Husqvarna. Well the old girl is now mine and I'm not willing to give up on it yet, to many fond memories of my grandfather cutting down trees for his saw mill.
Back to the point, the saw will always start on the second or thrid pull, unless it sits un used for a an extended time then its 5 or 6 pulls. It will sit and idel all day long, and you can run it wide open just as long with no load. The Problem comes to light when you try cutting with it, it will start the cut just fine but after 30 seconds to a minut of cutting the saw will try shutting off, if you leave it return to idle it will keep running but if you keep the throttle open it will shut off, after leaving it idle for a few seconds, then you can rev it up some eventually returning to able to run at wide open allowing you to start cutting again, but after 30 seconds or so the same thing happens again. I've fussed with the carb adjustments and dont seem to make much difference most times just makes it run worse.
PS the orginal problem with it was the original fuel lines deterioated and gunked up the carb, but that was an issue my dad fixed. I was just wondering if i should just replace the carb on it I stumbled accross a NOS carb for it on eBay and tempted to buy it to see if that solves my problem. |
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Post by lesorubcheek on Apr 24, 2015 10:00:42 GMT -5
Hello Herbert and welcome,
This is a guess of course, but the problem could be the vent which is located in the fuel cap. It'll have a sintered bronze plug with a rubber duckbill valve behind. As fuel is pulled out, this is supposed to let air vent in, otherwise it'll create a vacuum inside the tank and prevent fuel from being pulled in by the carb. It may be that yours is partially plugged allowing enough air to seep at idle, but not enough when you're cutting at throttle. Again, just a guess, but worth looking at before investing in a new carb. Its very typical for older duckbill valves to turn to mush and clog the vent on fuel caps.
Good luck,
Dan
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Post by herbertv2 on Apr 24, 2015 17:21:19 GMT -5
Hmm I'll check that out, hopefully its something simple lke that.
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Post by herbertv2 on Apr 24, 2015 19:35:24 GMT -5
Well I poped the little plug out of the fuel cap and the duck bil has turned to a sticky slime. I cleaned all the yuck out and tried to run the saw without the duck bil and breather, the saw runs the same still dies under load, this is with fresh gas and plug.
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Post by Brian VT on Apr 25, 2015 6:17:41 GMT -5
Start checking other rubber items like intake boot, impulse line, etc.
Carb. may not be fully clear or diaphram(s) not installed correctly?
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Post by sawnami on Apr 25, 2015 7:34:57 GMT -5
The pump diaphragm in the carb might be stiff from age. When this happens it tends to pump a lower volume of fuel.
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Post by herbertv2 on Apr 25, 2015 14:28:35 GMT -5
To the best of my knowledge the Super XL 925 dont have an actual impulse line its part of the intake manifold the carb mounts to. So your thinking the carb needs rebuilt again? should note my dad rebuilt the carb a few years ago, and replaced the fuel line. You think the impuse passage in the manifold could be blocked?
Could the fuel filter cause this issue? Dont know if my dad replaced that or not. I also noticed today that there is a small amount of gas that collected in the bottom of the compartment that the carb is located.
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Post by lesorubcheek on Apr 25, 2015 15:14:06 GMT -5
You're right, no impulse line. The fuel puddling could be the reeds letting fuel blow back. If it idles well, I can't imagine the reeds being bad enough to cause the problem you're having, but ya never know. Sounds like it would be worth opening the carb back up and looking for anything suspicious. If the filter let some particles past, you may find the screen inside the carb that's above the metering needle is partially blocked. Anything blocking fuel or preventing a good flow could be the cause of your problem.
Assume you have an HS 151 Tillotson carb. Think most 925s had these. There's a governor for high speed that prevents it leaning out, but I'm guessing if it was bad, you'd see a very rich condition at full throttle, and it's probably be constant, not after running OK for a short time. Still, something to think about. It's the brass plug with a slot for removal. If they go bad, you can use a small piece of brass, copper, aluminum, etc to plug the opening inside. Again, I wouldn't recommend starting there, but if the other suggestions don't pan out, its a possibility.
Dan
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Post by herbertv2 on Apr 25, 2015 20:04:02 GMT -5
Well I did actually time how long it takes for the saw to die out today, you can open the saw up and it will run a full throtle afer it has warmed up, just when you start a cut with it and put a load on the saw it will die out 5 to 10 seconds into the cut. Didn't have much time to work on it today, took the Craftsman and the ol Homelite XL out to cut up firewood
Knows it has a Tillotson carb on it unsure of the percise model, perhaps tommorow I will pull the carb apart and check it out, though if it's nice out will likely be cutting up more wood.
THanks for the help and suggestions so far.
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Post by herbertv2 on May 9, 2015 10:11:12 GMT -5
Well i rebuilt the carb myself with an actual OEM full repair kit from Tillotson after cleaning it out it really wasnt too bad at all inside alittle bit or varish build up from old gas, replaced the fuel filter after rinsiing the tank out with a bit of fresh gas and flushing the fuel line out, put a correct spark plug in CJ6, not sure what the plug in it was for wasnt what the parts guide called for the year of this saw. Also replaced the duck bills in both the fuel cap and the oil tank, and a new air filter. All I've managed to do was make it idle better, it still dies under load at WOT not matter where the high speed adjustment is set. Something i noticed is it dont smoke at all at WOT, both my Homelite XLs smoke a little while running WOT. And I'm running 93 octane gas with a 32:1 oil ratio on synthetic Weed Eater brand oil.
and someone previously must have did someting with the highspeed governor because there is red loctite on the threads and i can get the thing out all all and i fear triping the brass if i try to much force on it.
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Post by herbertv2 on May 9, 2015 10:33:16 GMT -5
I seen a few places have walbro replacement carb for the Super XL 925s anyone try those?
I honestly don't buy chainsaws to collect them, if I own them I run them so i'm not a stickler on keeping a saw 100% oem for collection purposes if it makes it run right I'll put the part on.
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Post by sawnami on May 9, 2015 19:25:54 GMT -5
Well i rebuilt the carb myself with an actual OEM full repair kit from Tillotson after cleaning it out it really wasnt too bad at all inside alittle bit or varish build up from old gas, replaced the fuel filter after rinsiing the tank out with a bit of fresh gas and flushing the fuel line out, put a correct spark plug in CJ6, not sure what the plug in it was for wasnt what the parts guide called for the year of this saw. Also replaced the duck bills in both the fuel cap and the oil tank, and a new air filter. All I've managed to do was make it idle better, it still dies under load at WOT not matter where the high speed adjustment is set. Something i noticed is it dont smoke at all at WOT, both my Homelite XLs smoke a little while running WOT. And I'm running 93 octane gas with a 32:1 oil ratio on synthetic Weed Eater brand oil. and someone previously must have did someting with the highspeed governor because there is red loctite on the threads and i can get the thing out all all and i fear triping the brass if i try to much force on it. The red Loctite should release when heated with a hot air gun. I think it takes around 450 degrees. |
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Post by Brian VT on May 10, 2015 7:07:39 GMT -5
I was going to ask if you've set the carb. to "4-stroke" at WOT, no load, but if you can't adjust it then you need to address that 1st.
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Post by herbertv2 on May 11, 2015 19:59:33 GMT -5
Got the high speed governor out of the tillotson carb and cleaned the carb again, and the saw still dies under load. Managed to get a NOS carb for it on ebay for $50 yesterday, I'm really hoping that fixes it running out of ideas. Asside from carb issues is there anything else that could cause this issue?
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Post by herbertv2 on May 14, 2015 21:25:50 GMT -5
Good News everyone, The Xl 925 runs like a champ now, still need some minor tuning tweaks to find that sweet spot, but it runs great with the new Walbro WJ-27 carb, has a very similar design to the original tillotson. Just wanted to thank everyone for all their help.
I'm still perplexed to what's wrong with the Tillotson, spotless inside and rebuilt but the saw refuses to run right with it.
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Post by powerking on May 28, 2015 17:31:47 GMT -5
herbertv2,
Glad to hear your final success on this adventure; been there, done that, and these stories continue..
When I gave/sold my brother a SXL-925 with the same Tillotson carb, it never ran correctly and exhibited symptoms like yours. We went through the fuel system and carb countless(it seems) times and it would do a few cuts and just start leaning out and die. It turns out that Walbro and Tillotson use a factory only installed non-removable sort of main jet check valve that fails and causes this lean condition. Another case in point; I have a tiny WYC-9 Walbro on a Ryobi blower that suffers from this problem too; all one can do is replace the carb. After installing a "kit" in the WYC-9 carb, same problem running lean (and a non-adjustable version). So much for carb rebuild kits that supposedly "fix" everything. I guess these companies want to sell carbs VS service kits.
Tom (PK)
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Post by mcycle12 on Feb 22, 2016 21:46:39 GMT -5
I am having the same exact problem as the OP with my 925. It starts fine, idles and accelerates fine, but when you put the chain to wood it lasts about 5 seconds before bogging out. Pull it out of the wood and it will accelerate again. Put it in the wood and seconds later it is dying. Here's what I've done to it:
Rebuilt the original Tillotson carb with a kit. Carb was cleaned in an ultrasonic cleaner and blown out. No change in running.
Found a NOS replacement Walbro carb on E-Bay. Put it on, along with new fuel line from the metal elbow back. No change...still bogging down.
Both carburetors were adjusted right on the high/low settings. The engine is running exactly the same with both carbs. The saw runs great until you put a load on it.
Checked the duckbill in the fuel cap. Cleaned the sintered brass plug in carb cleaner. Still bogging out.
Ran the saw with the vent in the cap open. No change.
Checked the line from the carb to the tank with a vacuum brake bleeder to see if it is sucking air. The line holds a vacuum without a problem when the end is plugged. No leaks.
Installed a new spark plug. No change. The plug is nice and tan when I pull it after cutting the ignition during a bogging spell. I think it's fuel delivery, not ignition.
Checked the impulse hole in the carb mount. When I put compressed air in it, the piston moves. I assume that means it's working. I'm using stock gaskets with the impulse hole lined up. The carburetor primed about about 5 pulls after I replaced the line, so I believe the pulse is working.
I'm at my wits end with this saw. All my mechanical knowledge tells me this is a fuel starvation issue. I really like it and want it running right, but it's driving me nuts.
Questions: If the saw is low on compression, will the impulse needed to operate the fuel pump be weak enough so that not enough fuel is pumped? I've yet to test the compression on this saw. How about the reeds? Will weak or broken reeds cause this problem?
This saw ran fine up until the time this condition suddenly began occurring.
Any help/advice will be appreciated!
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Post by Brian VT on Feb 23, 2016 7:41:00 GMT -5
Carbon buildup/blockage on muffler screen? If it can't blow out, it can't suck in.
Next I would check compression. Be sure the tester has a Schraeder valve on the tip that goes into the cylinder. Hopefully it reads 130#+.
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Post by sawnami on Feb 23, 2016 9:03:49 GMT -5
Will it falter/die if turned recoil down or clutch cover down while idling?
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Post by herbertv2 on Feb 23, 2016 10:40:16 GMT -5
Well for me I had good compression and good spark. I cleaned rebuilt the carb with an actually tilotson rebuild kit and replace all fuel lines filters and duck bills the saw ran exactly the same. no matter how it was adjusted. I eventually found a NOS walbro carb on Ebay a Walbro WJ-27, once the new carb arrive I installed it the next day, 3 pulls it fire up did a few small adjustments and cut a bit of Firewood with it, it ran great. I have it set to run a little rich, put it runs great and have been using it all this year and this winter to cut up the larger firewood my Craftman is too small for, it has also bailed out the craftsman when I pinch the bar.
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