Stihl Chainsaw

[Moeven]

I have a STihl 028 AV Super chainsaw that will run for a couple of minutes at full throttle. When I stop using it and let it idle it quits. I have put fresh fuel into it, cleaned the sparkplug, cleaned the air filter. What else should I do? I have taken the spark plug out and cleaned it several times getting a severe carbon buildup. Can anyone suggest to me a particular way to go with this? I have crews needing it up here in Alaska and they ar dependent on it.

[Reverend Blair]

The first thing I'd check is the filter inside the fuel tank. It gets gunked up and cut the fuel flow.

It's usually just a carborundum filter on the end of the fuel line inside the gas tank. Change it.

After that, clean the carb really well, or have it cleaned at a Stihl dealer. If you have a plastic carb, not sure if Stihl does that or not, it may be dissolving because of methanol in the fuel.

The other thing that comes to mind is a tiny hole or bad seal on the primer pump. It can suck air into the fuel system and kill the motor. That usually gets really bad really fast though, so you'd likely have noticed it by now.

[Egon]

Tweak the idle jet a touch but remember how much you moved it.

[J_J]

Who made up the fuel mix? Maybe to much oil, which will cause more carbon build up. Maybe go to a hotter plug. New plug. Set gap correctly. Factory setting on plug is not necessarily correct.

[Moeven]

So in order to get to the fuel filter, I am assuming that I will have to take the entire body off of this unit? Cleaning the Carb should not be too hard from what I can see. The fuel mix is approx. the 50-1 ratio. I have not seen a primer pump on this particular unit.

I am up here in Chignik Lagoon Alaska and have very limited access to supplies for this type of equipment. Thanks for the information.

[Egon]

If it's running properly at full throttle chances are the fuel/spark system is OK.

[PILOON]

So in order to get to the fuel filter, I am assuming that I will have to take the entire body off of this unit? Cleaning the Carb should not be too hard from what I can see. The fuel mix is approx. the 50-1 ratio. I have not seen a primer pump on this particular unit.

I am up here in Chignik Lagoon Alaska and have very limited access to supplies for this type of equipment. Thanks for the information.

The fuel filter is a weighted affair attached to the end of a soft rubber gas line inside of the tank.

Make a hook from a coat hanger wire and go fishing thru the gas filler opening.

Once pulled out of the tank you can examine/clean or replace it.
Not at all hard to do.

[RobertBrown]

I have a STihl 028 AV Super chainsaw that will run for a couple of minutes at full throttle. When I stop using it and let it idle it quits. I have put fresh fuel into it, cleaned the sparkplug, cleaned the air filter. What else should I do? I have taken the spark plug out and cleaned it several times getting a severe carbon buildup. Can anyone suggest to me a particular way to go with this? I have crews needing it up here in Alaska and they ar dependent on it.

I keep a Husquvarna and I can fix it but I guess the saw you have is a little different. Do you have the owners manual? It may have the carb adjustment procedeure in there, the husky one does.
Anyway I was able to find this, it's a pretty major job and you may not need to do all this depending on how bad the saw has been abused.

Small Engines (Lawn Mowers, etc.): Stihl 028, carburetor body, stihl 028

[RobertBrown]

Found this instruction on idle adjustment (see below), it exactly the same way you tune my saw so I think it may be correct. If you can get it to idle I'd try this first before I start taking anything apart the adjustment screws are easy to find and you should have three.
I found your owners manual and I down loaded it. I have it on my hard drive and can send it.
It's 19mb so it's way to big to attach. You will need to pm me pretty quick and I'll send it to you.

"Make sure the filter is clean, most are washable in water. The L adjustment adjusts low speed, the H the high speed. Screw both fully in and screw them both out 1 1/4 turns. Start the machine and adjust L for the highest idle speed, adjust the idle speed until the chain doesnt turn and the saw sounds right and adjust the H setting until a slight burbling is heard at full tilt and not at the most revvy setting. This allows for a slightly rich mixture that protects the engine from seizure and over revving".

[scuvnut]

I had a similar problem with my farm boss some time ago. I tried everthing you did and the stihl dealer told me to empty the gas, get some high test and use Stihl gas mix. It worked and I never had a problem again.