Saw problems

[sixteenacrewood]

Hi Everyone
I haven't posted in a while but hang out lurking pretty often.

I have a problem with my chainsaw I use for milling and cannot figure it out. For the record I did use the search feature and also posted in the chainsaw section here, but did not get any feedback. So, sence I am a chainsaw miller, I guess I'm meant to be here.

I have a Dolmar PS-9010 on a Panther pro cairage mill, 42" bar, and she also powers a 67" Alaskan. I run this saw a lot.
My problem is she is bogging down. Idles fine but will not reach top RPM wheather in the cut or sitting out of the wood.
I am a good mechanic (or so I thought). Here is what I have done so far

Muffler is not clogged (no screen) and exhaust port is clean
Cylinder, piston and rings are two years old and still look new. I broke her down completely for an inspection.
new plug, and spark looks good. I found a reference online about the spark should look blue, I think mine looks more yellow, but I could be wrong.
I put a used carb on it and she ran fine for about a half hour then back to the same problem.
I have a vacume pump and blocked the intake/exhaust and she held a vacume for 15 min without change.
I cleaned and sanded the coil contact and magnets on flywheel (400g paper) and where it contacts the saw body. magnets are strong.
fuel filter and fuel line are new
I also opened the fuel cap when it was running to see if the tank vent was clogged, but no change.
I run a lot of chainsaw gas and my mix is good, so def not bad gas.

Could it be the coil? I have never had one go bad so I don't know what the simptoms are.

Any help or ideas on what to try would be appreciated.

Thanks in advance

 

[betterbuilt]

That's a tough one.

Hows the carburetor?

Does it run fine with out the bar and chain? Double check your sprocket/chain/ bar and make sure your not mixing pitches/gauges. Don't ask me how I know this. Just double check. Check your bar tip.

The only coil issues i've had are is it wont start or dies when it's warm.

 

[sixteenacrewood]

Thanks Betterbuilt. Yes the bar and riping chain are matched and the sproket is in perfect shape.

I replaced the diaphrams and needle valve o rings when I got the carb.

I also went through the tune up procedure for setting the high and low needles.

 

[betterbuilt]

I guess I'd start over looking for simple things. Are the clutch bearing good? Check the fuel lines/impulse. Have you ran it with out the bar?

 

[sixteenacrewood]

impulse line and the coil are the only two things I havn't checked. I may break it down and just replace the impulse line.

Are there any tests for a coil, like resistance with an ohm meter. I did several google searches and havn't found any way to test one.

 

[betterbuilt]

It doesn't sound like a coil issue to me. I'm not saying it isn't. I'd start another thread over in the chainsaw section for the coil. Someone will be able to tell you how to test it.

 

[sixteenacrewood]

Thanks for the input Betterbuilt, I'll do that.

I think looking at all the small things is good advise so I think I'll start from scratch tomorrow and just check everything.

Thanks again

 

[Boon]

is there a screen built into or within the exhaust, recently I had a machine do what you described and looked for the/a screen to unscrew and clean but not there so took it to the mechanic and he placed a screwdriver in the exhaust port and gave a short hard jab, popped the inbuilt screen and away she went like new, no problems since.

 

[sixteenacrewood]

Thanks Boon, yes muffler and exhaust port are clean, I took the screen out long ago

 

[betterbuilt]

Did you change the screen in the carb? I'm still thinking it's a carb issue. I read the other thread and it sure seems like it is related to the carb. I'd go over your spare carb and see if you can find something you missed the first time. I built a pop off tester like gink595 recommended and that helped me test the carb by it's self. I look for the actual photo of the one I made.

http://www.arboristsite.com/community/threads/stihl-ms880-runs-at-high-idle-then-dies.165867/

http://www.arboristsite.com/community/threads/066-carb-issues.171064/

 

[betterbuilt]

 

[pond hopper]

Not familiar with the setup on a dolmar , but I've run into similar symptoms on stihl when the intake boot gets weak and partially sucks shut At higher rpms. Run it with air cleaner cover off and watch the rubber boot between carb and cyl. Something to check if all else fails.

 

[pa.hunter]

coil

 

[Rx7man]

With all the things you've checked on the fuel side of it, I'd start looking at the coil, and if there are any ignition boxes/points/condensers (I don't know that saw)

How does it sound when it revs out? does it sound/smell like it's too rich? Smoke? I've had a situation where I couldn't lean it out enough, and it was because the float level was set too high, so the fuel behind the float diaphragm would pressurize.. all sorts of nightmares with that.

I have had coils go bad too, and they just start acting funny sometimes.. no outright failure, but just not running properly.. same goes for the spark plug leads and the plugs too

 

[mad murdock]

coil, plug lead, or sparkplug. I would try a new plug first, if you already tried that, then the coil could have a crack or something in it, that is causing a electrical breakdown under load. A bad sparkplug, or lead will not always show up unless under load either.

 

[Calisdad]

sixteenacrewood, did you sort this out?

I'm having the same problem with my DCS 6401 with the big bore kit. New carb, piston, ring, fuel lines, fuel filter, air cleaner etc.
I thought I sorted it out when I found some sawdust in the tank valve and changed the fuel lines but after a slab and a half it dies.
I've been avoiding the coil as it's not cheap but I've read if you ever used a non-resistor plug you may have ruined your coil.

Frustrating as all get out.
Coils: is the Dolmar 038 143 041 (7900) interchangeable with the Dolmar 038 143 020 (6400) both red?