Raw gas in the air cleaner--Stihl 032 AV

[Fraidycat]

This old saw has cut a lot of wood through the years----still has 160# compression but now appears to be 'flooding' with raw gas coming back into the air cleaner. Thus, it won't run full rpm and is pulling down --losing power when cutting. When this started (and it came on suddenly) I installed a new carb kit but the flooding continues unchanged. I believe I have the diaphrams and gaskets installed correctly but don't know how to set the needle and seat to spec---or even if there is a spec. Also---I had a round disc left over---and a little screen. Both look like they may have gone in next to the needle and seat but I didn't want to try to pry the old one out and don't have a tool to install the new ones. I assume that these two items really arn't involved in my problem----I I have no idea where the raw gas is coming from but appears to be coming back through the carb intake into the airbox. I would appreciate any comment as to what may be the problem---and how to fix it. I am wondering if the needle and seat mechanism might be the key? It appears that the needle is normally 'set' closed and held there by a little spring under the fulcrum. When the diaphram senses vacuum it pulls down and the little pin on the diaphram presses on the fulcrum overcoming the spring pressure and lifts the needle off the seat? The 'atmosphere' vent hole in the cover is open and clear.
Adjusting the low and high mixture needles does not aleviate the 'flooding' problem---and these still run best when set at about 1 turn out from bottom. I am at a loss to understand what I can do to fix the problem---don't know if there is possibly some 'blowback' from a worn piston rings---but with compression being that high I can't figure there would be any blowback? Any suggestions would be appreciated. Lynn

 

[Gunther274]

Does that saw have reeds? If so I bet they are shot.

 

[NeoTree]

I'm no expert, but I've heard that a worn piston skirt on the intake side can cause fuel to be spit back out.

 

[Erick]

Sounds like the inlet needle is leaking over.... could be the metering lever set to high, metering spring not in right/fell out or over, or there is dirt in/on the needle seat not letting it close.

 

[Erick]

->HERE<- is a link to the manual for your carb should tell you all you need to know.

 

[Erick]

Another thing to check on that saw is to make sure the choke is functioning properly. The choke flap can sometimes come loose/off and partially block the intake causing it run overly rich. Separate the filter halves and check to make sure all is well.

 

[Fraidycat]

Stihl carb flooding

I've taken these suggestions into consideration----have made a minute adjustment of the needle fulcrum as per the Tillotsen manual and will be back to you folks with the results. Though the Tillotsen manual is not exactly as my setup it does appear that the operational principle is the same---and I am very glad to know how to check the 'setting' on the needle and seat setup----thanks for that valuable information. Very impressive ---thanks to all for the help!
PS---there aren't any reeds used on the intake on this one----good idea though.

 

[roncoinc]

Check out the carberator repair manual here..

http://www.divshare.com/folder/687788-a65

trouble shooting section

 

[Erick]

Though the Tillotsen manual is not exactly as my setup it does appear that the operational principle is the same---

Hedged my bets and got it wrong :blush:.... the 031/032 series also used the Walbro WA carb, but most (if not all) of the 032s I've seen were the Tilly HU.

->HERES<- a link to the Walbro info.

 

[ms290]

Hedged my bets and got it wrong :blush:.... the 031/032 series also used the Walbro WA carb, but most (if not all) of the 032s I've seen were the Tilly HU.

->HERES<- a link to the Walbro info.

you wouldnt happen to have those manuals for a Tilly HU 9C and a Tilly HS 10A would you?

 

[Fraidycat]

Raw gas in aircleaner

Eric--- My Carb is a Tilly HUS 1-A. I'm studying the diagram and manual provided by roncoinc now---hoping to find the error of my ways----but so far I haven't found a solution. I do know that the metering needle system is set up correctly now----with the lever arm even and level with the body----I had found that to be slightly high upon first inspection and had bent the mechanism just a little to get it to spec----but when I assembled and tried it again the gas continued to flow back into the air cleaner---not enough that the saw won't run---it starts and runs but doesn't snap up to full rpm like it should and won't pull ----again the air cleaner if noted to be full of gasoline.
I've got to believe that finding and fixing the cause of the excess fuel will restore my saw to full operation----but then---the saw has a lot of hours on it now and I'm hoping that neo tree nailed it------I'll keep working on this and will report back when I have better information.

 

[vhmtach38]

Had that happen on an 031av, couldn't tune after a new carb kit, I set the metering lever just a hair below the body, no more spitting gas.

 

[Grande Dog]

Howdy,
Possible plugged muffler or spark arrestor screen.
Regards
Gregg

 

[roncoinc]

If you went thru the troubleshooting chart there and still no
results check out as said the exhaust and make sure it is not plugged..
also make sure the needle and seat are clean so the fuel DOE's shut off.
you may also try the suggestion of lowering the needle just a "touch" more..
have fun

 

[Erick]

:agree2:
With all of'em.


Gregg may well have nailed it..... sometimes it's the simple things we overlook.

Check that muffler out.

 

[Fraidycat]

Carb flooding

OK---I've studied and checked the manuals ---thanks Eric and roncoinc for the links!. I've finally----I think----stopped the gas overflow by setting the arm just slightly low---as VhHMtach suggested. That setting is incredibly sensetive---just a hair width one way or the other makes all the difference as to whether the carb floods or not---Now I have stopped the flooding but have not won the war----It just doesn't want to run smoothly and labors to run at full throttle--and doesn't come close to reaching full rpm or cutting speed. I'll spend some time now trying to adjust the low and high speed needles-again--perhaps the mix just isn't right----but it acts like the timing is retarded. I'll have final information to post as soon as I exhaust my efforts to tune it. Does anyone know if the timing is adjustable or is it fixed?

 

[Erick]

you wouldnt happen to have those manuals for a Tilly HU 9C and a Tilly HS 10A would you?

The HU is the manual I gave above, ->HERE<- is the one for the HS.

Slight variations among carbs of the same model (HU) with different suffixes (9C) but the main jist of it is there.

 

[roncoinc]

I didnt think of it but the gasket goes next to the carb body and the diapham on top next to the cover..
aslo the diaphram can be put in upside down..make sure the protruding buton is what touches the lever..

 

[Fraidycat]

Raw gas in the intake

A plugged filter screen? Of course! That would explain the whole scenerio--the exhaust gas having nowhere to go would back pressure and blow back through the carb? Why didn't I think of that? Thanks Gregg---I'll check that out tonight.

 

[Fraidycat]

Raw gas etc

Well---back to square one-----I pulled the muffler---didn't look bad but cleaned the screen anyway. Put it back together and now can't get it to fire. There is spark---was running poorly before I pulled the muffler and I didn't do anything to the carb in that interim. I will put this up for now--busy with other matters----when I get back to it I'll see if I can find out why it isn't getting gas or why it won't fire now?