Author Topic: O28 Stihl runs rough  (Read 784 times)

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Offline middlefork

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Re: O28 Stihl runs rough
« Reply #10 on: September 26, 2012, 11:59:27 am »
Could I have condenser problem ?  I put everything back together and it fired up and ran for about 3 seconds then would not start or fire again .

Offline Vance in AK

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Re: O28 Stihl runs rough
« Reply #11 on: September 26, 2012, 12:42:50 pm »
Have you checked to see if you have spark &/or fuel at the plug?

Offline Al Smith

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Re: O28 Stihl runs rough
« Reply #12 on: September 26, 2012, 09:07:57 pm »
If it's got points it's an early model .They list three different ignition systems for that saw . The points type Bosc plus a solid state Bosc and a solid state SEM coil .

If it's got points it might not be a bad idea to burnish the points and reset them .I'm guessing at around 18 thou opening but I'd have to check to be certain .

Offline middlefork

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Re: O28 Stihl runs rough
« Reply #13 on: September 27, 2012, 10:38:25 am »
I checked and I have plenty of spark , the spark plug is firing on every pull .  I tried to start it and it would run rough for a while but would never smooth out . After a while while running rough it would die .

Offline Al Smith

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Re: O28 Stihl runs rough
« Reply #14 on: September 27, 2012, 05:04:39 pm »
I don't mean to sound like a smart azz but once I had the spacer gasket out of order on a Stihl 042 and it about drove me nuts .Made me so mad I banished the thing to the shelf for a year and half to punish it .

Now I know I had that carb apart at least a half dozen times and it never dawned on me and Lawd only knows how many carbs I've rebuilt .

I could get it fired up but the pot licker did just about what you are experiancing ,run a short and die on the vine .

Offline middlefork

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Re: O28 Stihl runs rough
« Reply #15 on: September 28, 2012, 02:59:24 pm »
I just took off the carb and cleaned every port , put all the gasket and diaphrams back in according to the diagram I got from the Stihl dealer . Put it back together and same thing . I don't know what else to do at this point .

Offline Al Smith

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Re: O28 Stihl runs rough
« Reply #16 on: September 28, 2012, 03:43:37 pm »
On the check valve side of the carb no matter if it's an Hu Tillotson or A (I think ) Walbro Wt carb there is a teeny weenie little screen .That thing is the last line of defense to stop stuff in the gasoline from entering the carb .

Fact the screen is so fine it will catch stuff that can pass through the fuel filter .If it gets clogged no amount of tugging on the string will get it started .It can be such a thing as it becoming clogged but appears clear . You about have to pluck it out with a needle and look at it .

It can be blown out with compressed air but hang onto it with a pair of needle nose pliers because if it gets away you'll never find it again .

I'm not saying that's it but I've been down that road before .Fact  blown a screen into orbit myself a time or two ,then dig through my junk until I find another .

Offline middlefork

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Re: O28 Stihl runs rough
« Reply #17 on: September 28, 2012, 04:06:52 pm »
Yeah that is the first thing I cleaned last week . thanks

Offline middlefork

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Re: O28 Stihl runs rough
« Reply #18 on: October 03, 2012, 08:45:13 am »
Still will not run .

Offline Vance in AK

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Re: O28 Stihl runs rough
« Reply #19 on: October 03, 2012, 12:07:31 pm »
When you are trying to start it does the plug get wet or stay dry?  Pull it through hard a 8 or 10 times with the choke on & then check.  Assume it feels like it's still got good compression?

 

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