help! stihl 031av problem

[philwarner]

Thanks again. flyboy,

I assume from your signature that you are familiar with avgas for uses other than chain saws. I got the Walbro manual and also found a Tillotson HU manual at http://www.tillotson-fuelsystems.com/manuals.html

I learned from them that I should have taken the metering needle out too while I had the carb apart. Guess I need to put in a kit and do that, especially if a new fuel line doesn't fix the problem.

All gas sold in Missouri where we usually shop is at least 10% ethanol by law, but I've since found one in Arkansas that carries 100% gas in one of the pumps and that's what I use now in all my small engines. Makes you wonder how much ethanol has really cost folks in addition to those studies saying that it takes more dino oil to produce ethanol than the energy it provides in fuel. I know it has screwed up several of my small engines including this nice Stihl chainsaw that I've owned from new in 1977.

 

[davidgpo]

While it's apart is it possible to intall lines that are resistant to ethanol fuels?:monkey:

 

[flyboy]

While it's apart is it possible to intall lines that are resistant to ethanol fuels?:monkey:

My experience ist that the ethanol messes up my metering gaskets in both the Walbro WA and the Tillotson HU3C.

 

[flyboy]

Thanks again. flyboy,

I assume from your signature that you are familiar with avgas for uses other than chain saws. I got the Walbro manual and also found a Tillotson HU manual at http://www.tillotson-fuelsystems.com/manuals.html

I learned from them that I should have taken the metering needle out too while I had the carb apart. Guess I need to put in a kit and do that, especially if a new fuel line doesn't fix the problem.

All gas sold in Missouri where we usually shop is at least 10% ethanol by law, but I've since found one in Arkansas that carries 100% gas in one of the pumps and that's what I use now in all my small engines. Makes you wonder how much ethanol has really cost folks in addition to those studies saying that it takes more dino oil to produce ethanol than the energy it provides in fuel. I know it has screwed up several of my small engines including this nice Stihl chainsaw that I've owned from new in 1977.

I am a low time private pilot.....so I use avgas for that.

If you have a walbro, you need the K10 kit. It sounds like you need a fuel line.

My dad bought one of the 031s I have new in Feb 76. He still has the receipt. I think it was the MS361 of that day because his friends were in awe of it.

 

[philwarner]

ethanol resistant fuel lines

While it's apart is it possible to intall lines that are resistant to ethanol fuels?:monkey:

David, the small line from the tank to the carb is just a straight small diameter line and can be anything that fits, but the in-tank line is a molded line with large diameter ends and a small diameter between; I have to go with whatever Stihl supplies.

 

[Duke M]

This is an old thread, but I just spent an afternoon cleaning the carb on my own 031AV and its symptoms are similar to the one in this thread. It will start and idle all day and will rev up freely as if it is ready to go, but when I put it in a cut, it will die in about 4 seconds. After it dies I can start it again it will idle as long as I let it. I took out the pickup filter, blew through it, and it does not seem to be plugged and while the carb was out, I tried sucking fuel through the line at the carb end and got fuel flow. I had replaced the fuel line and the impulse tube last year, but I have never replaced the points or even set them and I've owned the saw from new. It is just recently that it started dying in a cut as if it was not getting enough gas. Could worn points cause these symptoms? Is it a hard job to get to the points? Any advice will be appricated as I have a large oak that I need to cut and it is too big for any of my 015s. The 015s are great little saws for an old man to handle, but the 031AV is the standby for heavier work; I even have a 36 inch bar and chain for it for the really big stuff.

Had basicly same problem with my 031 ,changed to a atom module ( but I didnt reverse wires and ran great ) it would bog at fast speeds and idled rough ,couldnt adjust carb and carb was rebuilt ...so honed it put in new rings ...problem solved runs great ...bottom ring is for fuel and fuel was getting past bot ring when I took saw apart and looked in exhaut port and moved piston u could see slop in ring ,so maybe if u dont seem to have enough spark to burn fuel ,it could be hot enough but ur bottom ring could be weak ,it was easy to rering and made a world of difference ,but if u want to sell that old saw contact me thanks

 

[philwarner]

031AV soft fuel line

Had basicly same problem with my 031 ,changed to a atom module ( but I didnt reverse wires and ran great ) it would bog at fast speeds and idled rough ,couldnt adjust carb and carb was rebuilt ...so honed it put in new rings ...problem solved runs great ...bottom ring is for fuel and fuel was getting past bot ring when I took saw apart and looked in exhaut port and moved piston u could see slop in ring ,so maybe if u dont seem to have enough spark to burn fuel ,it could be hot enough but ur bottom ring could be weak ,it was easy to rering and made a world of difference ,but if u want to sell that old saw contact me thanks

Thanks for the reply, Duke. The new old stock 031 fuel line from ebay seems to have solved my saw's problem; I did have a scare because when I first installed it the small line from the elbow to the carb got kinked in re-assembly and it wouldn't run at all at first, but a second time of pulling the top cover and snipping a bit off the small line's length eased the kink and got the gas flowing again and I made a dozen cuts through an 18 inch diameter log without any problems. I had anticipated putting a kit in the carb, but so far have not; apparently the carb diaphragms are less susceptible to being softened by the ethanol than the rubber fuel line.

A friend who had to take a generator engine to a small engine repair place was told that half the shop's business now is from ethanol caused failures; when it takes 8 gallons of dino gas to plant, harvest, and process the corn to make 10 gallons of ethanol it sure doesn't seem like a good idea for anyone except the farmers and ethanol producers (and maybe the small engine repair guys).

 

[PatrickIreland]

A friend of mine, hippy type drives nothing but air cooled VWs. He thought for some reason that he was doing the world a favour by getting 10% ethanol gas. 6 months later - every fuel line dead, every bit of the carb that wasn't metal rotted out. He works on them for a living, so it wasn't a huge deal for him to replace them - but he no longer buys the stuff. Still a hippy though.:love1:
Spread the love, people!

 

[philwarner]

A friend of mine, hippy type drives nothing but air cooled VWs. He thought for some reason that he was doing the world a favour by getting 10% ethanol gas. 6 months later - every fuel line dead, every bit of the carb that wasn't metal rotted out. He works on them for a living, so it wasn't a huge deal for him to replace them - but he no longer buys the stuff. Still a hippy though.:love1:
Spread the love, people!

I'm sure we will never know the total cost of this ethanol idea in lost time, parts replaced, and frustration over breakdowns from ruined fuel line components, but I bet it would far exceed any benefits and probably even exceed the cost of bailing out the wall street and banking fat cats which is also coming out of our pockets. I seldom hear the lower energy content and reduced gas mileage of ethanol addressed let alone the damage it does to older cars and small engines.

 

[crzyhorse]

Polar opposites

I seem to be having a different problem than you all. I can start my saw on the first, second pull. My 031 electronic problems seems to be when the saw heats up I need to keep it at full throttle to it running. If it cuts off, I have to wait for it to cool down. When I first start it it will idle just fine, but if it heats up while idling it will cause the same problem. Someone was trying to tell me its a vacuum problem with the impulse hose, or the ignition. But if it was the ignition it wouldn't let me keep it at full blast no? It will cut like a beast while hot, but if it loses some rpms it will cut off. On another note someone tried to tell me you can fix a scored piston and cylinder, but I always thought once scored its trash. And last but not least it would be nice to give this saw a good thorough through, you all know of a good website to get the gaskets from? Any help will be greatly appreciated

 

[frecato]

http://www.mediafire.com/file/dnwykggj3jy/Workshop Manual Stihl 031 032.pdf

http://www.mediafire.com/file/yodmznt4zmn/stihl carburetor manual.pdf

http://www.mediafire.com/file/ufztmc...WalbroCarb.pdf

Hi flyboy I am a newbie and just purchased a Stihl 031 AV from craigslist and was looking for the service manual. I was able to download last 2 files but the manual would not download for me, any way you can send it to me? Thanks.

 

[flyboy]

Hi flyboy I am a newbie and just purchased a Stihl 031 AV from craigslist and was looking for the service manual. I was able to download last 2 files but the manual would not download for me, any way you can send it to me? Thanks.

It is 27MB. Too big to email.

 

[frecato]

It is 27MB. Too big to email.

Oh ok. I will try on another computer. Do you know if that link should still work?

 

[K5krawler]

Tillotson HU3C

Wanted to ask if anybody has had a NO-Start issue with the HU3C carb? It will run if fuel is manually fed across the throttle plate, However, will not pick up fuel itself. Now a few things I have done with no sings of the issue getting any better.
1. Cleaned Air filter and Disassembled carb. No real signs of anything seriously wrong however I feel the diaphragms are bad in the saw. (have seen bad diaphragms before in similar carbs).
2. Checked for obstructions in fuel lines. Fuel will enter carb with no problems.
3. Cleaned and checked fuel filter.
Any thoughts on if you guys think the carb needs rebuilt?

 

[Fish]

Remove the needle and hold the carb up to a light, see if you can see light through that passage.

 

[Rookie1]

Id totally clean the carb really well. Then clean it again. Put a rebuild kit in it. New fuel linesand filter,Fish will tell you about old style foam filters breaking down, and impulse line. If that doesnt help then Id look elsewhere.

 

[K5krawler]

Did more cleaning today. Off to Mr. Stihl for some parts for the Carb. Hopefully he can get them, if not...ripoffbay.

 

[K5krawler]

Saw is now running

Well, I got the carb kit and rebuilt it after work on Friday. Adjusted the screws 1 turn out and it fired right up. It took a few tweeks of the H needle to get it where it needed to be, but it runs now! Next I need a tach to tune in the saw while it is running. Does anybody have a max RPM for the saw?

 

[petepetersen]

I am having this porblem too and have found this thread very helpful . Is there any other fuel line that can be substituted that is more ethanol resistant ? Car kits too (maybe for other brands that have similar parts). - Thanks

 

[hvedlj]

old Stihl 031 Impulse line

I'm new here and I'm not sure if I'm posting in the right place.

I have found a lot of good information regarding my Stihl 031 in this forum. What I couldn't find was how necessary is it to use a stock impulse line on my saw. I replaced it with standard fuel line tubing and I am still having problems. It doesn't seem like it would matter since it just transferring a vacuum.

Thanks for your help.