STIHL 038 SUPER BOGS DOWN

[Tyl206]

Hi,
I have just done a full rebuild on my 038 Super and I have gotten it back together and seems to run well except when I go full throttle it seems to bog down but if I back off to about 1/2 throttle it seems to runs way smoother and powerful. Now I have adjusted the carb settings but it doesn't seem to help. The saw runs very well, starts up easy and will idle all day without stalling, only problem is I cant get good peak power without it bogging down. Of my knowledge it seems to run rich only when I hit the full throttle. Any ideas?

 

[Sleepy]

Hi,
I have just done a full rebuild on my 038 Super and I have gotten it back together and seems to run well except when I go full throttle it seems to bog down but if I back off to about 1/2 throttle it seems to runs way smoother and powerful. Now I have adjusted the carb settings but it doesn't seem to help. The saw runs very well, starts up easy and will idle all day without stalling, only problem is I cant get good peak power without it bogging down. Of my knowledge it seems to run rich only when I hit the full throttle. Any ideas?

Probably too lean instead of too rich.
Hows the fuel line and filter?
Did you check it for vacuum leaks or do a carb rebuild?

 

[Tyl206]

-Fuel line seemed to be still plyable and fuel filter is brand new and using Stihl HP oil mix.
-Impulse line is brand new.
-Carb was rebuilt 2 years ago but the paper gasket behind the carb was brittle and did not have a new gasket so I used Oil/Gas resistant sealant to mount carb.
-The only questionable leak is the intake boot where it slides on the cylinder intake..I have large zip tie holding it on, it is very tight but it is not the metal clamp.
-I thought it didn't have any leaks because it idles so well without stalling or rough idle.

 

[Mad Professor]

check if under cover on carb is full of sawdust

check fuel line with carb off, it can be pliable but have crack you don't see, bend it back and fort and look for tears/holes

cylinder bolts tight?

get rid of zip tie

 

[Tyl206]

check if under cover on carb is full of sawdust

check fuel line with carb off, it can be pliable but have crack you don't see, bend it back and fort and look for tears/holes

cylinder bolts tight?

get rid of zip tie

As I rebuilt the saw, I opened up the carb to make sure it was alright, I found a port with a screen full of saw dust. I cleaned it out. When I had the fuel line out of the tank I did not see any cracks or holes. The cylinder bolts are tight as well.
Now when I start this saw (has a hell of a pull) I put the choke on and try to start, usually it will fire up but die out. I then take choke off hold the throttle wide open and pull to start at the same time and fires up very easy and idles perfectly. Until I go full throttle I don't have any issues. I also have a new coil with new wires, when I installed the coil I placed a business card between the flywheel and the coil to set proper distance.

 

[Tyl206]

I can use this saw all day long, its just that I don't have that peak power to rip into wood.

 

[Mad Professor]

Was the OEM coil bad, and did the problem also arise when coil was changed along with other work?

If OEM coil was O.K. try that, could also be a sparky problem.

Also note that worn AV mounts can pinch a coil wire, and a bad wire might not short until you load the saw and the mounts flex. It has happened to me on a 038. Inspect your coil wire and the wire to the ing. switch

 

[L34]

Is the air filter OEM or AM?Is choke built into filter same as my 038 Mag?
My choke was pulling closed at WOT,filter was AM.
Try running with filter off.
Cheers,Chris.

 

[Tyl206]

Was the OEM coil bad, and did the problem also arise when coil was changed along with other work?

If OEM coil was O.K. try that, could also be a sparky problem.

Also note that worn AV mounts can pinch a coil wire, and a bad wire might not short until you load the saw and the mounts flex. It has happened to me on a 038. Inspect your coil wire and the wire to the ing. switch

I believe the old coil was fine but had seen a lot of use so I replaced it cause I had a spare. I believe the wire is in good shape but I will look that over.

 

[Tyl206]

Is the air filter OEM or AM?Is choke built into filter same as my 038 Mag?
My choke was pulling closed at WOT,filter was AM.
Try running with filter off.
Cheers,Chris.

Yeah I am using a AM filter. I will give this a try, I do see a mechanism inside. Ill check the saw out later tonight.

 

[Mad Professor]

Is the air filter OEM or AM?Is choke built into filter same as my 038 Mag?
My choke was pulling closed at WOT,filter was AM.
Try running with filter off.
Cheers,Chris.

Yes AM filters can choke things off at WOT

 

[Tyl206]

Is the air filter OEM or AM?Is choke built into filter same as my 038 Mag?
My choke was pulling closed at WOT,filter was AM.
Try running with filter off.
Cheers,Chris.

It did the trick! Alright so I cleaned the OEM filter and replaced it with the aftermarket. It totally fixed the issue where I was not getting power at WOT. I could tell the mechanism inside the AM filter was a lot weaker compared to the OEM. Runs awesome now. Thank you for all the replies!

 

[rocketnorton]

-Fuel line seemed to be still plyable and fuel filter is brand new and using Stihl HP oil mix.
-Impulse line is brand new.
-Carb was rebuilt 2 years ago but the paper gasket behind the carb was brittle and did not have a new gasket so I used Oil/Gas resistant sealant to mount carb.
-The only questionable leak is the intake boot where it slides on the cylinder intake..I have large zip tie holding it on, it is very tight but it is not the metal clamp.
-I thought it didn't have any leaks because it idles so well without stalling or rough idle.

get rid of zip tie

^^^ this

 

[L34]

Good you got it going.Took me about 5 mins to work out was wrong with mine.
Got AM car by on mine so thought it was that first.
Cheers,Chris.