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Stihl BG 86 won't start

Started by JohnG28, May 10, 2012, 12:40:20 PM

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JohnG28

Im having a problem with my Stihl leaf blower.  A few weeks back it died while I was running it and would not restart. Didn't have time to look into it, so I left it for a while. I have since tried to get it running, but not having any luck.  It has spark, getting fuel, and p/c are in good shape.  It seems like its flooding out. I have tried adjusting the carb but still nothing. I have the low adj at 1 turn out, high is at the stop. Fuel is fresh, filter is fine. Anyone have any ideas? Thanks.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

T Welsh

JohnG28, High and low speed screws should be set at 1 turn out from seated. Sounds like you have a fuel problem. Try to start it under normal conditions and when it wont fire, Pull the spark plug and see if it is wet with gas. also so double check for good spark while you are looking. If it is wet,you need to tear the carb down and blow all offices out with carb cleaner and air and reassemble it checking that the needle valve is not sticking and then make sure the jug is not filled with unburnt gas.(pull the started handle and blow air into the spark plug hole at least 5 or 6 times,put it back in and cross your fingers and say 3 Hail Marys and she should fire over. let us know what you find. Tim

JohnG28

Thanks Tim. I have the low out 1 turn, and the high side has a limit cap that I have not trimmed. I have pulled the plug when it won't start and its wet with fuel. Cylinder is wet but not full of fuel. Checked for spark and there is visible spark. That's what has left me puzzled. It sputtered a couple times today, no sign of life after that though. I'll look into it further.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

Paul_H

Check the spark arrestor screen in the muffler and see if it is plugged.A 5/8 socket should do the trick.
Science isn't meant to be trusted it's to be tested

JohnG28

The spark screen was also clean. Sorry, didn't cover all the bases at the beginning.  ::) It does have some fuel that has leaked out of somewhere and run down the outside of the casing. Not sure where its from, but may be related here. I'll see what some inspection yields tomorrow.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

joe_indi

Probably a damaged inlet needle in the carburetor is the culprit. Ethanol do cause it if not age.
If you are able to handle it as a DIY job, I think you can replace the inlet needle without even removing the carb from the engine.Just pull off the upper tube on the carb, remove the four screws that hold the primer bulb and priming pump, lift it up carefully, lift the metering diaphragm, loosen the Philips head screw, enough to pull out the tiny shaft that holds the lever in place, pull off the inlet needle.If it has a small ring on the rubber tip, it needs replacing.
Put in a new needle and reverse the steps and the job is done

Joe

JohnG28

One other question, does the idle adjustment need to be at any specific place to start? I don't think it would make a difference starting, as the engine is in high idle setting to start. Just a thought I suppose. I'll get her apart later today and see what I can. Thanks for the help so far.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

joe_indi

Quote from: JohnG28 on May 11, 2012, 02:08:22 PM
One other question, does the idle adjustment need to be at any specific place to start?
Loosen the idle screw till it looses contact with the lever of the throttle butterfly.
Now gradually screw it in till the butterfly is open a wee bit. Better still, if you have the carb off the blower, hold it to the light and screw in the idle adjustment till you see barely see a sliver of light at the lower side of the butterfly.
Do fine adjustments from this point.
Otherwise setting of the L screw will go wrong.

Joe

T Welsh

JohnG28, If you get sputter but will not fire and run. try a new spark plug. they are cheap and fast fix, before ripping into the carb. sounds like you are getting fuel,so make sure you are getting spark too. eliminate the simple things before moving on to more complex problems. let us know how you make out. I just did the same thing with an older BR400 I had laying in the garage for a year, last week. went to fire it up and it poured gas from the carb after a couple of pulls, the needle valve stuck in the open position and stayed there, I have seen this before so I new what to do. got inside the carb and sure enough it was not closing on its own pulled it out cleaned it and reinstalled it and made sure it opened and closed. put it back together and it fired right up. eliminate the simple things first before moving on to the bigger fixes. Tim

JohnG28

Well I finally tore into it today. Only a couple weeks late, but first chance I've had. So....new plug, no results. Not even a sputter. Pulled covers and air box off, seems fuel was coming out between carb and air box. This explained the fuel running out that I was seeing. Tightened up, tried again, nothing.  ::) Pulled the carb out, took off metering diaphragm, good shape.Pulled the inlet needle, looks like new. Pump diaphragm in good shape too. Blew it out quick, back together.  Nothing!!!!  >:( One.other thing I don't think I mentioned last time, the last time it was working in cut out running wot. Hasn't run since. Any thoughts or help are much appreciated.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

T Welsh

JohnG28, Once you verify that you are getting gas to the cylinder,you need to check for spark. pull the plug and ground it to the top of the cylinder head and pull a couple of times. If no spark,start checking all ground points along the wire to the switch and back. stopped running after it warms up is a classic symptom of a bad coil. but after they cool down they will usually start and run until the internals expand from heat and give out again. Tim

JohnG28

Thanks Tim. I did check for spark with the new plug. There is a good visible spark. Plug was wet with fuel again too. I'm very puzzled.  :-\
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

JohnG28

One other question here, could this condition be due to the metering lever being too high? If it were then the main nozzle would be partly open along with the metering needle, right? Not sure myself, but just thinking of some possibilities.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

Clam77

The plug was wet before you started pulling on it or after?? 
Andy

Stihl 009, 028, 038, 041, MS362
Mac 1-40, 3-25

T Welsh

JohnG28, Start at the beginning and pull the plug and clear the cylinder of all gas,blow it out with air and pulling the starter cord a bunch of times and then put the plug back in and try starting as usual. pull the plug back out after a dozen tries. If its wet,see how much! is there a lot of unburnt gas in the top end? If so you will need to adjust the metering needle. It sounds like you are getting to much gas right away and its drowning the spark plug. Tim

Clam77

Andy

Stihl 009, 028, 038, 041, MS362
Mac 1-40, 3-25

JohnG28

So I tried today. Pulled on it about a dozen times, dry plug.  This isn't getting better. Any other thoughts?
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

T Welsh

JohnG28, Float needle is sticking! either on or off. Tear the carb apart again and make sure it has full range of movement. Take the screw out holding the metering needle and polish the shaft with fine emery cloth and reinstall it and then move it up and down to see if it is free. Then try again to start it. One way to verify that it is not another problem is to dry everything out and pour a little bit of mix gas down the spark plug hole and fire it up. It will try to fire until it burns the amount of gas poured into the hole! Good luck! look at it this way, you are gaining valuable experience as you fight through this problem and you are not paying shop time for someone else to fix it. Tim

Al_Smith

More times than not if you just install a rebuild kit in the carb it will solve all those problems . ;)

joe_indi

Today I had a BG86 that came in for repair with a sort of similar problem.
When the starter was pulled, it would just kind of burp and, that's it, it just wouldn't start.
The problem was the stop switch wires were kind of mashed together in a groove that seats the starter cover.
So, the ignition keeps cutting off.
On a spark plug you get a spark, but maybe only erratically.
To confirm that this was the problem, I disconnected the stop wires from the ignition module and tried starting the blower.
It fired on the first try.
Strangely, this was a fairly new machine which the customer had brought with him from USA  when he came back home for his annual holiday.
Maybe, instead of looking only into the carb, you should also look for other  causes like this one.
You never know.
Maybe a flywheel that's moved out of its position due to a sheared key.
Maybe something else.

Joe

JohnG28

Thanks for the continued help guys. This is a fairly new machine, I bought in in fall of 2010. It hasn't seen a lot of use either and I generally run gas out if my equipment is going to sit a while. This is the first piece of equipment I've had any this type issue with, so the experience is good for me. The diaphragms seemed like they were in good shape, but I suppose I don't have a lot of experience to judge by. I'll try pulling it apart again and see if I can get this straightened out. If not I'll try a carb kit. One good thing is after figuring this out I'll be able to get this ms200t I just picked up running. Needs a carb kit or new carb. Thanks for the help again.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

Al_Smith

Quote from: JohnG28 on June 01, 2012, 06:36:29 PM
   carb kit. One good thing is after figuring this out I'll be able to get this ms200t I just picked up running. Needs a carb kit or new carb. Thanks for the help again.
When you get on that thing if you can't get it post away .I can write  volumes on those little hot rods . ;)

JohnG28

Well today brought more of the same.  I tried bypassing the stop switch with no results, so that doesn't seem to be the problem.  It did sputter a little with a shot of fuel in the spark plug hole but wouldn't start still.  Tore the carb apart agian, checked the metering needle.  It was clean and moved fine but seemed like there was a little play before the metering lever would engage it.  Is that how it should be?  There was some exhaust smoke barely coming out the exhaust even though I didn't get it running, making me think I'm close.  The metering diaphram was sort of cupped also, so maybe I need to just put in a carb kit and try from there.  Have to try to pick one up on Monday and try that.  ::) Thanks for the help!  Oh, on a positive note, I did finally put the blower away and put the carb back into that 200t.  Got that running!  It needs some work still, but at least it runs! :)
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

joe_indi

If the resultant noise wont be a bother, try starting the blower with the muffler removed.
Does it start without the muffler?
All this is narrowing down the cause to either a clogged muffler or an ignition problem.
Ignition problem could be either a sheared flywheel key or a short circuit inside the ignition module.

Joe

JohnG28

I'm quite certain the muffler isn't plugged, I've had the screen out and can see inside, nothing at all. As for ignition issues, how would I go about judging if this is the problem? I have seen spark and its not the switch as I tried bypassing it.
Stihl MS361, 460 & 200T, Jonsered 490, Jonsereds 90, Husky 350 & 142, Homelite XL and Super XL

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