Stihl 038 Adjustment

[Bear0422]

okay, I've rebuilt the Tillotson carb on my Stihl 038 Super. It is an older model Stihl.
1) I start the saw and it runs very fast,fast enough that the chain is moving. I have tried backing out the Idle Adj. Screw, but the only thing that happens is that it dies.
2) I have the carb screws backed out each one turn, but the saw still runs fast enough for the chain to spin.
3) What am I doing wrong?

I here of people using a Tachometer and checking the speed of the saw. How do you adjust the RPM of the saw? Is this done by the gap on the flywheel?

I need some guidance from some of the Gurus on here. Actually, any help will be appreciated!

Thanks,

 

[pioneerguy600]

Not a guru but you may need to back out your L setting to over a turn out, sounds like the engine is running lean at idle, if you get the adjuster out more than a turn and a half there is other problems. Set the LA so that the throttle stop screw just touches the tang on the carb linkage, then turn it in one turn.
Pioneerguy600

 

[adkranger]

Did it just develop this problem?

First check your settings, particularly the L & LA. If it stihl spins at "idle" then you might have one of two problems generally; 1) air leak or 2) weak clutch springs (if idle is correct).

Check the fuel, impulse lines for cracks. Check the intake manifold for rips/cracks.

 

[Bear0422]

Doesn't matter if you're a guru, I appreciate the help.

The saw was one I picked up from a friend. He had not run it for some time. I got it to start once, but could never get it to start again. I replaced the ignition module,because I had no spark, and then I rebuilt the Carb. Since I have rebuilt the carb, the saw starts okay, just that it idles fast enough to make the chain run.

 

[pioneerguy600]

Doesn't matter if you're a guru, I appreciate the help.

The saw was one I picked up from a friend. He had not run it for some time. I got it to start once, but could never get it to start again. I replaced the ignition module,because I had no spark, and then I rebuilt the Carb. Since I have rebuilt the carb, the saw starts okay, just that it idles fast enough to make the chain run.

Try setting the carb up using the LA and the L like I posted previously and if this does not make it stop spinning the chain it might just be that the clutch springs are streatched allowing the clutch shoes to drag on the drum, do you have any idea if the saw is running too fast at idle?

Pioneerguy600

 

[Bear0422]

Yes it is running too fast at idle. At least it sounds like it. To me it is just short of a "scream" so to speak.
Man, I really appreciate the help and info. Keep it coming, we'll eventually figure this one out.

 

[pioneerguy600]

Yes it is running too fast at idle. At least it sounds like it. To me it is just short of a "scream" so to speak.
Man, I really appreciate the help and info. Keep it coming, we'll eventually figure this one out.

Ok ,if it does not adjust out on the carb settings I have posted then it is very likely you have an air leak, that extra air getting into the crankcase will cause an engine to run that way. A vac test will tell the story, it is the first thing I do to a suspected case like yours.

Pioneerguy600

 

[pioneerguy600]

Check out this thread ,it will explain a vac test.

http://www.arboristsite.com/showthread.php?t=42768&highlight=vac+test

Pioneerguy600

 

[JustinM]

Ok ,if it does not adjust out on the carb settings I have posted then it is very likely you have an air leak, that extra air getting into the crankcase will cause an engine to run that way. A vac test will tell the story, it is the first thing I do to a suspected case like yours.

Pioneerguy600

Good advice & I agree with the thinking here.

 

[Bear0422]

Okay everyone, I have not done a vac test yet. However, I just went outside to mess with the saw, tried to start it and it wouldn't start. I then noticed fuel leaking out of the muffler. What have I done wrong? I know it is getting fire, I've checked it several times, what else can I do?

Any help or ideas would be very much appreciated!

Thanks,

 

[pioneerguy600]

Fuel can only get through your carb to get inside the cylinder then out through the muffler. Your carb is flooding. Most often caused by the inlet needle valve not shutting off the supply of fuel, can be caused by foreign material under the needle on the seat. Also if the metering lever is set too high this will keep the needle valve open and allow flooding, same goes for the order the gaskets are placed in, if the diaphragm is placed onto the carb body and then the gasket placed on top, this is the wrong order, the gasket goes on first the diaphragm on top of it and then the cover.

Pioneerguy600

 

[pioneerguy600]

You can also flood the engine by pulling out the choke and then pulling it over too many times, the choke causes a lot more fuel to be drawn into the engine on every turn of the cranlshaft/piston stroke. How many times did you pull the engine over with the choke on?

Pioneerguy600

 

[Bear0422]

I pulled it several times, probably around 10 or so. Let it and me rest, then tried it again, this is when I noticed the fuel coming out of the muffler. I guess I should take the carb back down and have a look at it. I adjusted the needle valve the way they said to, but maybe I got it opened just a little too much. Thanks for the info.

 

[pioneerguy600]

I pulled it several times, probably around 10 or so. Let it and me rest, then tried it again, this is when I noticed the fuel coming out of the muffler. I guess I should take the carb back down and have a look at it. I adjusted the needle valve the way they said to, but maybe I got it opened just a little too much. Thanks for the info.

Not sure if you are pulling over that many times with the choke on. A saw should start within 3-5 pulls with the choke on, if it does not then it is not getting fuel properly but if you continue to keep pulling then most often the engine will flood.
Pioneerguy600

 

[Bear0422]

Jerry, thanks for the help. I will try it again tomorrow night, if it doesn't start after 3-5 pulls, I'll probably take the carb down and make sure the diaphragm and gaskets are in right. And once I do that if it doesn't work, I'll take in to my local stihl repair shop and let them have a look at it.

 

[Mad Professor]

Not sure if you are pulling over that many times with the choke on. A saw should start within 3-5 pulls with the choke on, if it does not then it is not getting fuel properly but if you continue to keep pulling then most often the engine will flood.
Pioneerguy600

I'll agree unless they have been sitting.

If ca. 5 pulls on choke don't do it , set the throtlle 1/2 open with no choke and try again, 5 pulls (covers being flooded here) . Still nothing? Try a regular cold choke again.

I've saws that will start 2-3 cold always, unless they have been sitting and the line/carb is dry