Stihl ms 230

[GardenKit]

I too, am not too old to learn it seems. I have never found a blocked vent to have such a quick effect as it takes a little while to build up a vacuum, especially as fuel which shakes about expands as it evaporates, causing pressure in the tank. It is this pressure which is vented by the breather as an imbalance between fuel pressure and atmospheric pressure acting on the carb will cause problems with fuel flow.

 

I wonder if this 230 problem will turn out to be something else, or will I have to eat my hat!

Edited August 5, 2012 by GardenKit

[mick irwin]

right guys, ive cleaned the breather, it was ok to be honest and ive checked all of the piping cleaned it aswell with a small piece of pipe, spudulike i couldnt find any grub screws in any of the pipes so i have put a picture in of the back of my saw, all the pipes are clear and ive rechecked the fuel filter etc. so were clear with that, but it still cuts out? i had the carb off,just so im sure mate the breather is to the right under the yellow H screw isnt it? ive had every pipe thats there off and cleaned and i split the breather apart and all was good inside, im also going to upload a video of my starting the saw and you can se it struggle then i open the fuel tank and away she goes again? like i said thanks everybody for your help on this as i am clueless now im afraid, ill put the video link up as soon as it loads,

[mick irwin]

 

hi there again, this is a video of me starting my saw, its running and revving then it starts to struggle, you can see me opening the fuel tank and revving it up again and no problem? i do this twice on the video, hope this helps confirm a problem, thanks for your time again,

[spudulike]

Thats a shame, I had hoped Barrie had one of those leather stetsons and the thought of him chewing on it would have made me smile:thumbup:

 

Your breather is marked as below, you need to take it off and suck on it:blushing: and see if you can draw air through it, if you can then it is OK.

 

Going back to you loosening the fuel cap and the saw working, if the saw was on its side, it could be the turning of the saw loosened up the muck that is in the carb gauze filter or it is possible your pumping membrane in the carb is perforated - I have seen the pumping flaps having holes worn in them.

 

I would check the breather and then do the same test with loosening the fuel cap and see if it works again because if it does, it will lead to the answer!

[mick irwin]

ha ha shame about the hat thanks spudulike i did your test on the breather pipe and when i cleaned it, nothing came out (thankfully) and if you follow the breather pipe up it splits to the breather and the primer, i also checked this, also clear too, so mate for fear of sounding stupid is it just to check the carb now? is that a job for me or should a mechanic be doing that? i did peek inside the carb opening the top and the bottom yesterday, it looks full of tiny screws and filters but i didnt prod too much, on checking i did turn the saw on its side to take the fuel cap off,

[spudulike]

Seeing your video, it is possible the removal of the fuel cap and replacement is pressurising the fuel tank and forcing more fuel in to the carb making the saw work correctly and then it dies once the pressure isn't there to force the fuel past the blockage.

 

Try one last test, remove that breather tube where it meets the fuel tank and run the saw up, if it bogs then investigate the carb - probably crap in the gauze filter. If the saw runs well then it is the breather.

 

On the history of the saw, has it run fine in the past, has the saw ever run OK in your ownership? Just seeing if the saw has gone from working to not working in your ownership.

[mick irwin]

thanks again mate, great advice here, i will try your other test tomorrow, my neighbours developed a twitch when i use my saw i bought my saw from a mate who used it for working wood and crosscutting, this was about 3 1/2 years ago then i got it for carving and tree work, the saw had barely been used it just wasnt big enough for him, i used it at least 10 hours a week between cutting for my fire, tree work but mostly carving,for two years without any problems until the flywheel broke a year ago and the saw sat idle really for a few months when i went working down south,and it was when i was there it struggled to keep running,but not as bad as it does now, for the last 4 months it will just not run at all, does this help?

[spudulike]

Know what you mean about twitchy neighbours - my saws ara a little hot though and testig out a fully ported and muffler modded 064 probably didn't help - it was a little loud:lol:

 

Yes it helps alot, it tells me that the saw isn't a bad un off ebay that has been messed with.

 

The lack of top end can be just down to not enough fuel and turning the H screw out by 1/2 a turn may sort it - stndard H setting without limit caps is

1 1/2 turn out from fully in. If the H screw hasnt been set to this it is worth investigating but if the saw has gone from working fine to giving problems and the H screw hasn't been adjusted then it probably isn't the issue.

 

Try the test on the breather and lets hear how you get on.

[mick irwin]

thats brilliant thanks for all your help spudulike very very appreciated, i have a carving bar im getting from rob d for my bday and im itching to get it ordered once my saw works ill let you know cheers again spudulike

[GardenKit]

The fact that it had been unused for a while could be key here, the carb may have been 'gummed' by stale petrol and the seat of the inlet valve may be damaged, along with a change in flexibility of the metering diaphragm.

 

Assuming that your tests have shown the breather to be clear, and vacuum eliminated, the next step will be to check the effects of pressure.

 

When the tank pressure builds a little with vaporisation of the fuel the pressure is relieved through the fuel pump after which it meets resistance from the fuel inlet valve. If the valve is damaged, or the lever spring pressure is weak, then the inlet valve may let excess fuel through to the metering valve, causing the saw to run rich and loose power.

 

Releasing the fuel cap will release the pressure and allow the inlet valve to shut correctly.

 

If this is the case then a good carb overhaul will sort it out. Alternatively, test out this theory by fitting a known, good carb first.

 

Just another wild idea, but you never know. And I really dont want to eat my genuine Australian leather hat.