Let's play diagnose the farm boss chainsaw.

[1Alpha1]

I figured this saw didn't need one as it's not a pro model.

Partially seized exterior muffler bearing?

 

[fearofpavement]

The ignition switch was working fine. This saw had no physical damage, the cylinder was OEM and other than being really dirty when I got it, seemed to be in pretty good condition.

 

[old-cat]

Throttle not fully opening.

 

[cus_deluxe]

crank bearings then?

 

[Wood Doctor]

Well, when you pulled the carb and then put it back in, perhaps you sealed up the impulse hose connection without knowing it. Should that have been leaking air, the top end power would have been in severe trouble.

You said, " Saw could rev but no power at all." That's a typical problem with a lousy impulse hose connection leaking air. When that happens, the carb is helpless.

 

[fearofpavement]

Review thus far:
I checked the piston/cylinder. ok
I checked the compression. ok
I replaced the carb with a known good one. ok
I tested the fuel and impulse lines. ok
I checked the fuel vent. ok
I checked the gap on the coil. ok
I checked the fuel quality. ok
The saw passed a pressure and vacuum test which tests the carb boot as well. ok
I checked the fuel filter. ok
I checked the air filter. ok
I replaced the spark plug. ok

 

[Kenskip1]

The Halogen level was low and had 15% Ethanol in it.Muffler bearings are worn out, Ken

 

[cobey]

try different coil?

 

[fearofpavement]

So what's left?

Here's what it was:



The plug wire was separated and corroded where it goes into the spark plug boot. I changed the coil with a used one and the saw fired right up and sounds normal. Haven't put a bar on it yet but am convinced that was the problem. This did not seem ignition related to me as the saw would consistently start but was boggy. I'll add that to my diagnostic memory bank now. Put about 5 hours of labor in figuring this issue out. The engine never "clipped" "missed" or cut out like ignition issues usually display themselves, it just ran gutless. If I was starting over, I would suspect compression and fuel. Never thought an ignition issue could feel and act like that.

 

[cobey]

odd deal...

 

[1Alpha1]

So what's left?

Here's what it was:



The plug wire was separated and corroded where it goes into the spark plug boot. I changed the coil with a used one and the saw fired right up and sounds normal. Haven't put a bar on it yet but am convinced that was the problem. This did not seem ignition related to me as the saw would consistently start but was boggy. I'll add that to my diagnostic memory bank now. Put about 5 hours of labor in figuring this issue out. The engine never "clipped" "missed" or cut out like ignition issues usually display themselves, it just ran gutless. If I was starting over, I would suspect compression and fuel. Never thought an ignition issue could feel and act like that.

That was gonna be my 3rd guess........................

 

[cus_deluxe]

i think old cat was pretty close then with weak spark

 

[fearofpavement]

Yep, old cat got it.

 

[cus_deluxe]

nice well done

 

[Saw Dr.]

If you haven't run it in wood yet, check the flywheel key. Retarded timing will do just what you described.

 

[Milkman31]

This is odd. I just yesterday sent my brothers 210 home with him after I worked on it off and on for over a month. Same symptoms as above and I was ready to bust it in half and buy him a new one lol!! Last thing I did was take the plug boot off and clean the metal spring inside that sticks inside the plug wire and bam runs like a champ.

 

[gaspipe]

I worked on one of the railroad's Stihls a few days back. An 026. Did the same thing. Pulled the muffler and there was a bridge of carbon nearly closing off the exhaust port. Chipped it out, threw away their premix (into my Crown Vic's fuel tank), mixed some new fuel, and it ran fine. Weird.

 

[Philbert]

I was visiting a 'well established' saw shop with GrizzlyAdams86. While we were there, a younger guy brought in a saw (Poulan? Really can't remember) that was acting funny. The shop owner gave it a couple of pulls, set it down on the counter, pulled out a screwdriver, and removed a totally plugged spark arrestor screen. Started the saw back up, and it appeared to run fine. He told the owner that he could clean and reinstall the screen or run it like it was, without it. "$5".

I asked him how he knew. He said, "Just sounded like it".

Philbert

 

[fearofpavement]

If you haven't run it in wood yet, check the flywheel key. Retarded timing will do just what you described.

I had the flywheel off and put it back on. Key is intact.

 

[cobey]

I really dig the 390's if all 290's were 390's they would have a better rep