Trouble Under Load Again

[WarmGuy]

My Craftsman chainsaw let me down again yesterday. Once again, it would start, but would die as soon as I tried to rev it up.

Here's the link to my post about this last time:

https://www.hearth.com/talk/threads/13438/

I changed the spark plug, and dusted off the air filter, and still had problems. I then thoroughly washed the air filter, and was finally, after many tries, to get it working again. That is, I'd start i up, then use the choke to get the RPMs up, and finally, I could squeeze the trigger without it dying. I used it to cut a full truckload of 18 inch diameter pine, and it worked OK, but I'm not sure it was providing max power.

Today I will do some experimenting (like put in the old plug) to see if I can determine what the problem is.

Here's a specific question: I get the impression that just dusting off the foam air filter doesn't help much, but thoroughly cleaning it with soap and water does help. Does that sound right?

In any case, if I can get this working well, I'm going to sell it (with full disclosure), and buy a Husky or Stihl. I need a saw that's ready to go at a moment's notice so that I can take advantage of scrounge score.

 

[Wolves-Lower]

Yes, clean the air filter with soapy water, then rinse well.
It sounds like a carburator-gas issue.
Have you taken it to a shop?

 

[kevin j]

change to fresh fuel first, and pickup filter
check the fuel pulse line and the fuel suction line to carb. If any cracks or porosity it wil suck air.

If it ran with choke, then eventaully ran ok, possibly just not warmed up, or adjusted too lean on the H & L screws.

Warm it toally, then adjust H & L screws, out is richer, CW in is leaner.

 

[granpajohn]

If it ran with choke, then eventaully ran ok, possibly just not warmed up, or adjusted too lean on the H & L screws.

Warm it toally, then adjust H & L screws, out is richer, CW in is leaner.

I had the same problem with my Husky when new. (2005 maybe). Kevin's solution was right on. Problem was, in order to sell in CA, these carb adjusters had plastic limiters on them. They had to be cut off for correct adjustment, then she ran like new again. I complained to Husky, (now owned by Electrolux I think), and they would only say I must take it to a dealer (under warranty I assume).
This was explained here: http://www.arboristsite.com/showthr...4&threadid=6711&highlight=remove+and+limiters
(I hope I have that right...it's been a long time).
Maybe you've already looked, but Arboistsite.com is very good for saw info.

Don't know if that helps much, but please post on if it works.

 

[Hanko]

check your mixture screws, its probably got a walbro carb. the setting on both should be approx one and one half turns out from the full in possition. fine tune from there. If it sat with gas in the carb and it gooped up, you will need to take the carb apart and clean it out

 

[pinewoodburner]

Check your fuel line and fuel filter. My Pouland did the same thing. Worked great, then started dying when I reved it up. Checked the fuel filter and it was off the fuel line. Had to replace my fuel line since it was bad.

 

[WarmGuy]

OK, here's the result of my experiments today:

1. I put the old spark plug in, and it ran fine.

Conclusion: The spark plug was not the problem.

2. I cleaned the air filter thoroughly, and it had some problems, and then ran fine.

Conclusion: After I clean the air filter, there's some residual moisture, even though I try my best to dry it.

So I think the basic problem is that the air filter gets easily clogged, or the high humidity around here (often 80%) makes it damp. I clean it, and I have problems for a while until it dries out.

Note that the last time I used it, I ran it for about one hour -- that was just one month ago.

What do you think about my conclusions?

 

[cmonSTART]

If you have to use choke to get the RPMs up, it's running too lean on the high end. Turn your high speed adjustment out (CCW) about a half a turn and see if that makes a difference. If you're up against the limiters, some folks are known to pull them off, or cut them off carefully.

 

[kevin j]

agree, it is lean.
patially plugged filter restricts air somewhat, richening it up. The choke would make it worse.
choke adding fuel, means it is lean.
You can remove the limiters and richen the H setting. This COULD be a bandaid though if the saw is taking air from a fuel line issue or something, but start with a good tuneup.

The plastic caps have a tab that prevents richening more than a certain amount once pressed on. EPA in its wisdom….. Fine if the saw is in the design range, but if not, more pollution and seized engines from lean condition.

Stihl has a tool to remove the limiter caps. About $7 but you can use a fine sheet metal screw to do the same thing. Basically, the tool is a left hand fine threaded tap about #4 or #6 size. It screws into the center of the plastic cap and as it threads in it bottoms on the head of the actual metal adjusting screw and pushes the cap outwards to remove it. I think, not sure, but the left hand thread is so that the resistance or friction tends to open or bring the screw out until the limiter tab hits the stop, then pulls the cap. If it turned CW, inward, there is a small chance the screw would bottom in the carb body before the tab hit on the other direction. Thus, torqueing on the tool could drive the adjusting needle into the seat and damage both. Being LH thread prevents that.

If you use a fine screw to act as a puller, hold the cap carefully with needle nose to keep it from turning CW. May have to remove the shroud around the saw.

You may need to replace the caps if there aren’t springs on the screws. The friction of the plastic to the case is what holds screw position. If so, get new caps (50 cents for a stihl, which is probably a typical Walbro carb and may fit yours) and cut the limiting tabs off so they are just a round plastic cap now.

There are sites on the web that have video and sound of saw rich and saw lean. Madsen's had one, but their site has been down a year. Lean it starts overreviing and screaming. Rich it starts to 'fourstroke’ and burble sound. If you are not familiar with that, take the screw out CCW a bit until is seems to start sounding strange. Go back in just a bit until it clears. That will be quite rich, but safely away from the lean limits that can overrev bearings and seize pistons in the bore from the combustion heat.

k

 

[brad068]

Make sure the carb is tight. I don't know if its a spigot or flange mount but check that. A loose pulse line or blocked pulse hole,gasket diaphragm ripped sounds like a possibility too. Also those carbs (zama maybe) have a fine filter screen inside the carb under the top plate before the needle/seat valve that can get plugged too. If you can remove the caps on the mixture screws, screw out the high mix, first keeping track of turns in to seat and blow out the passage maybe dirt in there. Finally, use Amsoil premix and 100% gasoline!

 

[jeffman3]

Sounds like we have had similar problems. I ended up taking mine back to the shop many times, and finally, just told them I wanted my money back and got a Husky. My craftsman would run fine for about an hour then die when you let off the throttle. Sometimes it would start, sometimes it wouldn't. The mechanic at sears told me "...they just run like that" I told him to give me money back then, because "I need a saw that will run for more then an hour and a half". Your time in the woodlot is to valuable to spend it messing with the saw, trying to make it run. I thought I was buying a quality saw (Craftsman is a good reputable name, right?) I found out differently. Do yourself a favor and get a true quality saw, you will not regret it. Get a Husky and don't worry about it.

BTW the Husky 350 is an awesome saw I have the 20 bar and love this saw!! Did I say you would be very, very, happy with a Husky 350?????

 

[Bartman]

How old is your saw? Some of the smaller Craftsman/Poulan saws made a few years ago had really troublesome carbs, they were Walbros. Currently I have one of these hanging in my shed. These saws are of the 2.0-2.3 cu in variety,and your best bet is to find a new carb. These units don't lend themselves to be rebuilt very easily, success rate for rebuilds on them is very low. I have a stockpile of these carbs that are bad and refuse to chuck them with the hopes of someday conquering them, but I don't think it's gonna happen. There are passages in these carbs that are just too small and obscure to clean, and with the early "cracking" of today's gasolines this situation can occur relatively quickly. Just my 2 cents worth.