Stihl 011AV runs a few seconds and dies, I'm stumped

[OcFerris]

Hi, I'm relatively new to CAD and some weeks ago it got the better of me when I bought a Stihl 011AV that looked like it hadn't seen a lot of use. I was told "it had gas sitting in it for a while but should be OK". Fair enough. I think it's one of the older models, all orange, before they changed to white but it does have electronic ignition. Anyway, I checked compression (145psi), flushed the tanks, put in a carb kit, cleaned the arrestor screen, new spark plug (the original looked fine BTW), new fuel line and just gave the saw a general going over and cleaning.

Well, that all resulted in a saw that starts easily but won't stay running. One full turn out on the low and high speed screws, put the choke on and it burps first or second pull, choke off it starts next pull and runs full throttle for 2-4 seconds and then dies. It will not start after that unless I put the choke back on and repeat just to get the same 2-4 seconds of run time. I had repeated this enough at one point that the saw was warm enough for me to start adjusting the low mix screw leaner. I kept leaning it out until it got where I could start the saw and keep it running and idling well enough. I put it aside and when I tried later to start it cold it wouldn't go. I checked the settings and found the low mix screw was only open 1/4 turn and the idle screw was all the way in. I know that's not right and it would not start again until I adjusted the low screw back out to something more reasonable.

I've since double-checked the carb build to be sure it was adjusted properly & none of the passages were blocked, checked fuel flow both with and without the filter, replaced fuel line again and tried running with the gas cap cracked (in case the vent wasn't working). No difference. Thinking the carb was junked I even replaced the original WT21 with a WA99 from an 010AV. That didn't help either. It's weird, the saw acts like it's running out of gas when I cold start it but the one time I got it running it sounded like it was running rich (heavy 4 stroking) but that could just be a high speed adjustment I never had time to get quite right.

I have not done a vacuum test as I don't have the equipment (yet). I do have a set of oil seals on order because an air leak is the only thing I can think of that I haven't tried. From what I've read about the symptoms of an air leak though, that's not my problem. I could be wrong. I have been before and it's likely it'll happen again.

Any direction you can give me would be appreciated. I'm not sure what to do next. Thanks!

 

[OcFerris]

Anybody think I'm on the wrong track going after an air leak or should I exercise a little more patience with carb adjustment(s)? I've fixed a few saws but just haven't come across enough different situations to gain the experience needed.

 

[redunshee]

I've had similar issue with a saw after cleaning and rebuilding the carb. Was going to get a new carb but as a last ditch effort I borrowed a Ultrasonic cleaner and stuck the disassembled carb in it. That did the trick. Now works great.
My experience with bad seals is that the saw will run but will be hard to adjust carb, due to the air leak. Have you checked or replaced the vent line? It runs across the saw next to the fuel line and out the right side of the saw. There is a cover above the clutch as I recall. Did you replace the fuel fliter? Forgot ecerything you mentioned in your post.
Bob

 

[Fish]

Inspect the gasket below the carb, make sure there are no rips around the impulse port, also inspect the block and plate underneath for problems, warps, cracks, etc....

 

[cpr]

Did you pull the whole muffler off? I've seen a couple of these that had a lot of carbon build up at the exhaust port.

 

[Whiskers]

The last 011 I worked on had a bad case gasket and was allowing extra gas to pour in the cylinder eventually resulting in flooding. I would think if you had an air leak it would only run right if the carb were set rich, not lean and want to race at regular settings. Maybe you've got a similar gasket leak to what I had. Although, mine would also empty a half full gas tank into the case overnight, so it became pretty obvious. I also don't know if case gasket issues are common on these saws, I haven't worked on enough of them to know.

 

[deereguy]

What Fish said, He knows what he's talking about.

Replace the gasket under the carb. Make sure the carb is firmly screwed down and gas line not crimped when the filter and cover is put on.

 

[OcFerris]

Thanks for the responses! I'll try to answer;

I've had similar issue with a saw after cleaning and rebuilding the carb. Was going to get a new carb but as a last ditch effort I borrowed a Ultrasonic cleaner and stuck the disassembled carb in it. That did the trick. Now works great.
My experience with bad seals is that the saw will run but will be hard to adjust carb, due to the air leak. Have you checked or replaced the vent line? It runs across the saw next to the fuel line and out the right side of the saw. There is a cover above the clutch as I recall. Did you replace the fuel fliter? Forgot ecerything you mentioned in your post.

I soaked the carb for a couple days in a seafoam/gas mix and blew out the holes both ways (and my eye at least once) with gumout carb cleaner. Carb rebuild did NOT include squelch plug replacement as flow through that area seemed OK. The vent line was checked and is working. I did not replace the fuel filter but did try running without it just in case.

Inspect the gasket below the carb, make sure there are no rips around the impulse port, also inspect the block and plate underneath for problems, warps, cracks, etc....

Double-checked this last night. Gasket above and below the reed plate look good. No tears or areas that look suspect. Plate and carb are making a good clean impression in the gasket material. Impulse hole isn't covered and appears to line up with the carb. The reed itself is lying flat against the underside of the plate (I assume that's correct) and there are no gaps. I can't find any cracks. I laid a straight-edge on the surface and it appears flat. I have new gaskets ordered but they haven't come in yet. I do have a spare (used) plate and will try that probably this weekend. I'll let you know how that works out.

Did you pull the whole muffler off? I've seen a couple of these that had a lot of carbon build up at the exhaust port.

Did that when I inspected the p/c. There was some carbon buildup but really nothing more than a coating. However, the spark screen was probably 70% blocked with buildup. I burned that off and it's clean now but it does make me wonder if the saw was having problems or how well it ran prior to me getting it.

The last 011 I worked on had a bad case gasket and was allowing extra gas to pour in the cylinder eventually resulting in flooding. I would think if you had an air leak it would only run right if the carb were set rich, not lean and want to race at regular settings. Maybe you've got a similar gasket leak to what I had. Although, mine would also empty a half full gas tank into the case overnight, so it became pretty obvious. I also don't know if case gasket issues are common on these saws, I haven't worked on enough of them to know.

I don't either but I'm pretty sure I'm not losing gas into the case. That doesn't mean it's not leaking air somewhere else. It just doesn't seem like an air leak. I do NOT know that from experience, only from what I've read here on the forums.

What Fish said, He knows what he's talking about. Replace the gasket under the carb. Make sure the carb is firmly screwed down and gas line not crimped when the filter and cover is put on.

Replacement gaskets are on order but the ones already there "look" OK. If I get desperate I may try some gasket sealer until the new ones arrive. I'm really trying to avoid that eventual cleanup if I can. Definitely not a lot of room for fuel line routing on this saw but I think I've got it pretty good. I did try running with the air cleaner and cover off to be sure it wasn't getting crimped.

---

As mentioned above I do have some new gaskets, filters, etc on order. I ordered these things from the local dealer 7-8 weeks ago and all the dealer has to say is "they're not in yet". This dealer is usually very good at getting parts in a week or less and it's never taken longer than 2 weeks for anything I've ever ordered (newer saws though). Are parts for these saws that hard to get? Are there other sources to get parts? I see most of what I want (except the oil seals) on ebay but I just can't bring myself to buy parts for what has to be a 1000% markup.

Anyway thanks for the feedback.

 

[a. palmer jr.]

On my 011 the spark plug wire shorted out to the case when you turned the saw a certain way. If I were you I would replace it even if it looks good.

 

[OcFerris]

solved!

I like to follow up for the benefit of others who may be having trouble. The saw had two issues;

1> I used this as the excuse I needed to justify the purchase of a mity-vac vacuum/pressure pump. (used but good enough!) It had a small air leak. I didn't bother to track down where it was and just tore the saw down and replaced all the gaskets and the oil seals. It ran much more consistently after that but was still running very rich. That led me to ...

2> ... a rookie mistake. When I rebuilt the carb I simply put it back together the way I took it apart. When I checked the carb rebuild for the 3rd time I realized the gasket and diaphram were reversed and that was causing too much fuel flow. I put them in the correct order and now the saw runs great!

Thanks to all for the help!

Hmmm, I think I have enough leftover parts to build another one ...

 

[Wood Doctor]

Bad Fuel Filter?

I had the same problem with an 010 AV and it turned out to be (1) a bad fuel filter and (2) the breather tube from the tank was rotted out. Those old fuel filters just plain give up and can eventually shut the engine down after running awhile. Replacing that and the breather tube fixed everything.

The location of the carb and its design is one of the weaker points of this saw, but it sure runs nicely for an old beast when all systems are go. Built like tanks.

 

[OcFerris]

..... but it sure runs nicely for an old beast when all systems are go. Built like tanks.

I'm looking forward to putting it in some wood this weekend and getting the carb fine tuned. It's a small saw but you need those too. I agree that parts of the design are a little archaic by today's standards but they seem to function well. I plan to replace my MS170 with it. I modded the 170 a little and it runs very well but I've always been disappointed with build quality (too much plastic).