028AV Super fuel problems

[ketch]

My 028 AV Super will run one or two big revs if I give it a "prime"" of fuel. Will restart a couple of times but dies.

Filter is clean. Hi and Low adjusted according to the manual.
I would much appreciate some suggestions on an efficient stepwise method to correct the problem.

Since I found the knowledgeable guys on this great site I have started to get my "dead" saws back running.
Thanks to all.

 

[Lakeside53]

If your fuel filter, fuel lines, and carb inlet screen are fine, and your impulse hose and boot are intact, then the most likely cause is a seal leak - in the case of the 028S, the clutch side. It's a PITA to put in even with the sleeve tool from Stihl - the inner lip rolls up and the retaining spring pops off.. use the OEM seal with the blue center - less problems than the black aftermarket seal.

You really need to pressure test the saw to find the problem.

 

[028AV Super]

As I had the same problems with my 028 Super last year, it ended being the impulse hose. Just looking at it I couldn't tell, when I took it off and strech it, I could see all the weather cracks between the flexes (loosing pressure to run the carb). Also recommend you change the intake rubber hose (carb to cylinder) as well while you are in there. They are only few bucks at the Stihl store. Good Luck,

 

[justin028]

stihl 028 super bogging down

I recenly put some new parts in my 028 av super because it was bogging down while cutting up small pine trees. I replaced the air filter,fuel filter, gas line, rebuilt carb, and still having the same problem. Also i noticed it wont rev up right even if it is warmed up and it idles ral low.. But it will rev upand idle right if you hold the throttle down and shake the saw real hard then it works just fine for the hole job. Doing so it will rev and idleright but still bogs down from time to time under even the lightest loads. So i have to pull it out of the cut in the tree and use full trottle to cut it and event then it starts to bog from time to time. I got fed up with it and took it to a stihl technician and he said there wasn't anything wrong with the carb it is adjusted perfect. He said it might have been the gas tank vent but it is clean as cen be. Needles to say it still is bogging down quite frequently even if i hold it at an angle to cut a lim off over my head, or hold it at a downward angle to cut up logs on the ground.Do you have any idea what the problem may be.

 

[Fish]

Go back into the carb and remove the needle/spring/lever, and blow out the
passage underneath, and visually verify that it is clear, it probably is not.
Blow out everything else while it is apart again, then reassemble.

If you will do this, and not rule it out as absurd, you may even thank me someday. The old fuel filter's foam insert was crumbly.........................

Naaahhhh, just ignore me, I am used to it...............................

 

[justin028]

thanks for the info i'll try it. but i went through and took those peices out before when i rebuilt it and cleaned every thing out of it and it was clear. One orther quick question is ther a setting on the tension of the needle screw because there is a single screw that holds the hole neadle in place and when i asembeled it before i tightened it snug but that made the needle to far in the hole so i had to back it off so the needle would function properly.Because i was told by my uncle that there is a specific setting the neadle is placed at and i should have noted how far or down the needle was resting at.:chainsawguy:

 

[Lakeside53]

If you are talking about the Carb H&L screws... they are 1 to 1 1/4 turn out from snug to start... then tune from there...

If you are talking about the metering spring and inlet needle INSIDE THE CARB, then I'm really confused.

 

[Dan Forsh]

You don't adjust the position of the needle with the screw that holds the arm on. This should be tightened down all the way. You should bend the arm if the position needs adjusting.

Have a look on page 6 of the attached manual and you'll see what I mean.

Dan

 

[PES+]

My 028 AV Super will run one or two big revs if I give it a "prime"" of fuel. Will restart a couple of times but dies.

Filter is clean. Hi and Low adjusted according to the manual.
I would much appreciate some suggestions on an efficient stepwise method to correct the problem.

Since I found the knowledgeable guys on this great site I have started to get my "dead" saws back running.
Thanks to all.

It sounds more like you need a rebuild kit with new diaphrams and needle lever and spring and a new screen.

It might be a bad seal but unlikely as the seal would have to be completely missing to have the symptoms you describe. The carb is not pumping fuel and if the impulse line is not broken with a large gap it should pump some fuel.

 

[PES+]

thanks for the info i'll try it. but i went through and took those peices out before when i rebuilt it and cleaned every thing out of it and it was clear. One orther quick question is ther a setting on the tension of the needle screw because there is a single screw that holds the hole neadle in place and when i asembeled it before i tightened it snug but that made the needle to far in the hole so i had to back it off so the needle would function properly.Because i was told by my uncle that there is a specific setting the neadle is placed at and i should have noted how far or down the needle was resting at.:chainsawguy:

You have a different problem and it is needle and lever. Do as Dan suggested as having the pivot pin loose will cause the problems you describe.

 

[Lakeside53]

I had a saw last week where the guy had put the spring IN the needle valve hole, then mounted the needle/arm, and didn't even notice that the arm is supposed to be hooked onto the needle... just crushed it all down with the screw. But it get's worse - thought he had to use ALL the gaskets that came in the K20 WAT kit... He swore he had put it together the exact same way it came apart. I fixed all that mess and found his problem was a loose (distended at the fitting) impulse hose (031).

 

[1953greg]

You don't adjust the position of the needle with the screw that holds the arm on. This should be tightened down all the way. You should bend the arm if the position needs adjusting.

Have a look on page 6 of the attached manual and you'll see what I mean.

Dan

does anyone have a link like that for the walbro carbs??

 

[justin028]

Checked for problem

Well i took apart the carb yesterday and took out the whole needle assembly and checked out the whole where the needle goes in, and it was clean as a whistle so was the screen on the other side of the hole. I just rebuilt the carb about a month ago so the gaskets are all new. When i put the needle in and tightend the screw that holds the whole needle asembly in place i noticed the back of the lever was not siting flush with the top of the well it sits in so i bent it up a little. Put the carb back together and messed around with the h and l screw to get it runing, and went to go test it out on some small logs and it seems to cut alot better now, but only time will tell. I think with a little fine tuneing it should run a lot beter and not so slugish.