Stihl 028av issues

[GruntHMC]

FNG to AS.
I have a Stihl 028AV that has persitantly given me problems.
I cleaned the carb and changed the plug. It ran great for one day.
Now, it only likes to run when leaned out about 1/4-1/2 turn of the high.

I looked throught the exhuast port and found a black streak on the piston. The "streak" is smooth with no rough edges.

Any guidance?

 

[FullCry]

I'm no expert but sometimes cleaning the carb once doesn't do the job. You may have to do it again for a port or two may still be clogged up. Also make sure the fuel filter isn't stopped up and that your adjusting the carb correctly. I don't know your experience with saws but if I mentioned something you already know then no offense. Also check the compression first. FullCry

 

[striperswaper]

how is the air filter?
are you sure you are going lean not rich?

 

[GruntHMC]

The Air Filter is older but not in bad condition. I have cleaned it several times just to make sure.
I will check the Fuel filter today. I noticed that on several posts.

I will have to get my hands on a compression guage.

If I adjust the H to a richer mix then it smokes and runs too rich but it is adjusted so low now I am afraid of causing more severe damage.

I don't have much experience with Saw motors but I am familiar with how they run and I can usually spot things that are wrong.

Thanks for the input!

 

[bitzer]

Did you check the fuel filter in the tank or the tank vent? You may also want to throw a new spark plug in it and see what happens. They are cheap and it could be that simple. Otherwise check you fuel line for cracks or impulse hose for damage. If it is running rich it will not suck air, but at what would be the correct mixture a cracked line will suck air and cause the engine to run lean.

 

[matt9923]

rebuild the carb, compression test. vac/pressure test, fuel cap vent....
use a tach if you don't know how it is supposed to sound

 

[longbar]

check the plug on it. If its running lean it will be white and bubbly looking. If it looks more tanish or brownish it getting enough fuel and your needle and seat in the carb might be leaking or not adjusted right.

 

[GruntHMC]

Guys,
You are all a tremendous wealth of info. This was a pathetic issue that I figured out after a month of senseless "tinkering".
I pulled the fuel filter and the fuel line. All looks good. I rebuilt the carb and lost the screen filter, so I need to get a new one.
Here is the sad part!
The spring in the air filter that keeps the choke from closing was missing, thus choking off and on as it ran.
I put in a new spring and the saw runs as it should. I feel like an idiot after assuming the worst.
After I adjusted the carb I ripped through a few logs like soft butter and motor laughed and asked for more!
Thanks for the help.
Matt

 

[timbrjackrussel]

The question is, where did the spring go?? I hope it wasn't sucked into the engine!
I had a 028 where the spring was not mounted to the brass cotter pin. Seems that the owner of the saw thought that the cotter pin held the air filter together and removed the pin to clean the filter. It wouldn't run right after that. I won't forget that one!