Stihl 038 Woes

[Gord404]

wolf creak has the kit and so does H&L

 

[Mad Professor]

That is not the correct Bosch spark plug. WSR6F

I think those may be made in China or Brazil now?

I'm using NGKs more often now. BPMR7A

 

[djg james]

That is not the correct Bosch spark plug. WSR6F

I think those may be made in China or Brazil now?

I'm using NGKs more often now. BPMR7A

Thanks, that's exactly what I'm going to use. After re-gaping to 0.020"

 

[Bob Hedgecutter]

Your "made in china" carb looks to have come in a genuine Stihl box and labelling- so it highly likely genuine. Stihl owns a plant in China to supply like items.
Your original is a Tillotson- they came with those, or earlier 038's came with Bing carbs. This is normal- not unusual and they are not marked for Stihl- they got carbs from known carb manufacturers- just like they did with cylinders and pistons.

 

[djg james]

Your "made in china" carb looks to have come in a genuine Stihl box and labelling- so it highly likely genuine. Stihl owns a plant in China to supply like items.
Your original is a Tillotson- they came with those, or earlier 038's came with Bing carbs. This is normal- not unusual and they are not marked for Stihl- they got carbs from known carb manufacturers- just like they did with cylinders and pistons.

If I need a carb kit for the "China" carb where would you get it? Doesn't matter, all the same? ebay?

 

[Bob Hedgecutter]

If I need a carb kit for the "China" carb where would you get it? Doesn't matter, all the same? ebay?

Are you getting a bit ahead of yourself? Thought it worked well when on the saw?
That carb is the current available Stihl Zama offering for the 038/380/381- C3-S148 so a Zama kit for that carb will be available almost anywhere- Zama RB-167

 

[Mad Professor]

Are you getting a bit ahead of yourself? Thought it worked well when on the saw?
That carb is the current available Stihl Zama offering for the 038/380/381- C3-S148 so a Zama kit for that carb will be available almost anywhere- Zama RB-167

Tillotson makes carb kit for theirs and Bings. The Bings were on the later 038M. They also have a new manufacture replacement.

The 038S and Mag were same size. The plain 038 was a smaller Tillotson

 

[djg james]

Are you getting a bit ahead of yourself? Thought it worked well when on the saw?
That carb is the current available Stihl Zama offering for the 038/380/381- C3-S148 so a Zama kit for that carb will be available almost anywhere- Zama RB-167

It does until buried in the wood. Then it surges. I don't have much experience diagnosing/repairing saws. Just thought maybe some of the rubber parts in the carb may need to be replaced. Planing ahead, plus I have other saws to work on too. Knowing where to get the reliable parts is just part of the process.

 

[djg james]

I've been working on my 038 and I put on a new tank vent. I was hoping that would do the trick. Went to the log yard today to test, but nope, have to keep pumping the throttle to keep it going.

To make matters worse, the flippy cap now leaks. Took it off twice to check for debris and saw nothing. I can't believe I damaged it setting on my bench. Leaking fuel cap wouldn't cause the problem described above?

I'll order a couple new ones. Might as well pick up some new fuel filters and hoses as well. I put a new fuel filter on but didn't change the fuel line. In the meantime, I'll check the impulse line again. @ballisticdoughnut, can you completely remove the impulse hose by the method you described earlier? Using hemostats and fishing around? Can you replace them too in the same way without anything else?

 

[Mad Professor]

Look over your fuel line well. I've had 038 fuel hoses go bad and you can't see the cracks without taking it loose from the carb and bending it a bit. The cracks being between the ribs on the hose

In my case the saw would miss in the cut almost like an ignition problem.

Also check the ignition lead to the plug. If the AV buffers wear out the wire can get damaged/pinched and give an intermittent short. Had that happen too.

 

[djg james]

Look over your fuel line well. I've had 038 fuel hoses go bad and you can't see the cracks without taking it loose from the carb and bending it a bit. The cracks being between the ribs on the hose

In my case the saw would miss in the cut almost like an ignition problem.

Also check the ignition lead to the plug. If the AV buffers wear out the wire can get damaged/pinched and give an intermittent short. Had that happen too.

I did check the spark plug wire, but I'll check it again.

 

[Mad Professor]

I did check the spark plug wire, but I'll check it again.

Are the AV buffers in good shape? That wire ends up getting pinched between the fueltank/handle assy and the crankcase

 

[djg james]

Are the AV buffers in good shape? That wire ends up getting pinched between the fueltank/handle assy and the crankcase

The AV buffers were changed when I change the gas tank a couple years ago. I'll still check the wire, though

 

[ballisticdoughnut]

@ballisticdoughnut, can you completely remove the impulse hose by the method you described earlier? Using hemostats and fishing around? Can you replace them too in the same way without anything else?

Yes the impulse hose can be removed and installed as I described previously. Make sure to remove the air filter cover and top/cylinder cover. You’ll need all the wiggle room you can get.

 

[djg james]

Another couple of stupid chainsaw repair questions. To recap, my 038 surges when I pump the throttle. I took the carb off to aid in the replacement of the fuel line (PM?). I found the ground wire had cracked insulation and was setting on top of the metal throttle rod. When the trigger is depressed, could the wire be shorting the saw out? I say no, but what do I know.
View attachment 1153414
Obviously, I'll replace the wire when I get a new one. Just thought maybe this might be the cause of my problem.

While I have the carb off, I thought I'd try to replace the impulse line (PM?). I've got the top shroud/cover off. Anything short of removing the gas tank can I do to make access easier? Someone here said just to use my surgical skills and hemostats. Don't know if I can.

Lastly, while I have the carb off, I thought I'd take both side covers off to check on the status of the rubber membranes. They ARE right below the covers aren't they? I'd like to buy another kit. Are AMs good enough?

P.S. I posted these same questions in the Firewood thread in the chainsaw section.

 

[Bob Hedgecutter]

The wire- you are correct- the break in the insulation and proximity to the rod could allow current to jump the gap- but it needs then for the rod to be able to carry that current to earth/ground to kill the spark.
There should be two wires on an 038 going through the "firewall" of the air box- the black one you show that is the trigger contact- and another (blue from memory) that has an eye connector at each end, one eye goes under the metal tab the switch contacts- held by the screw that holds the metal to the base of the air box- goes up through the same grommet at the top and down to where the top cover bolts to the crankcase- this grounds the switch in the plastic tank models.
Personally I change position of this wire to ground on the AV mount so it does not get forgotten of the top cover is removed.

Impulse line is fitable with the tank insitu- but is not dead simple to do and yes, long hemostats are a big help to get it seated on to the cylinder barb.

I have used AM carb kits- but we do not have E fuel either. If you are not sure about anything or have doubts- use genuine kits.
The main carb parts you are wanting to replace are directly under the cover on either side- but pay attention to both the order they are fitted in and the orientation of them as you replace them.

 

[djg james]

The wire- you are correct- the break in the insulation and proximity to the rod could allow current to jump the gap- but it needs then for the rod to be able to carry that current to earth/ground to kill the spark.
There should be two wires on an 038 going through the "firewall" of the air box- the black one you show that is the trigger contact- and another (blue from memory) that has an eye connector at each end, one eye goes under the metal tab the switch contacts- held by the screw that holds the metal to the base of the air box- goes up through the same grommet at the top and down to where the top cover bolts to the crankcase- this grounds the switch in the plastic tank models.
Personally I change position of this wire to ground on the AV mount so it does not get forgotten of the top cover is removed.

Impulse line is fitable with the tank insitu- but is not dead simple to do and yes, long hemostats are a big help to get it seated on to the cylinder barb.

I have used AM carb kits- but we do not have E fuel either. If you are not sure about anything or have doubts- use genuine kits.
The main carb parts you are wanting to replace are directly under the cover on either side- but pay attention to both the order they are fitted in and the orientation of them as you replace them.View attachment 1153426View attachment 1153428

Thanks. I do see both ground wires and how they function to shut the saw down. I was hoping it would be a quick fix.
I did manage to replace the impulse line using my surgical skills. I'm thinking of applying to Med school now .

Both the impulse and fuel lines were a little softer than the new ones I replaced. I don't think they failed by collapsing, but it didn't hurt to rule them out by changing.

And I checked the spark arrestor screen in the muffler. It was clean.

 

[djg james]

Put everything back together to see if the hoses made a difference. Surprisingly the saw runs great. Either it was the hoses or the wire.
Thanks everyone.

 

[president]

Put everything back together to see if the hoses made a difference. Surprisingly the saw runs great. Either it was the hoses or the wire.
Thanks everyone.

next time drop the rear av mounts on the rear and pull down on the handl for acsess to the lower cylinder /impulse hose location

 

[djg james]

As I stated in the "Firewood Scrounging" section, I'm resurrecting this thread because the saw is acting up in the same manner. I'll recap everything I've done to it now so you don't have to read through the whole thread.

This may not apply to the current problem, but i don't want to leave anything out. Years ago I cracked my fuel tank and eventually installed a plastic AM tank. It worked fine for a while but the choke/shut-off lever was hard to engage and finally broke. I replaced it with a AM lever. Ever since, WHEN COLD, I have to shoot some 50:1 mix into the air filter before I choke it. Saw started right up. Wouldn't have to choke it once it was warmed up. It's like the choke lever didn't completely close the choke. Anyway minor inconvenience that I could live with. And probably not related to current problem.

Back it January, the saw would die once it hit wood and I would have to pump it to get through the wood. This is what I posted about initially in this thread and these are the things I've done to get it working smoothly again.
1) Change fuel line/filter
2) New spark plug
3) Cleaned air filter in case oil residue from evaporated 50:1 was clogging the filter
4) New impulse line
5) Checked spark arrestor screen
6) New gas tank vent

After I did this, it worked fine. I don't know what the actual problem was.

So now it May, it's acting the same, or worse. I shoot 50:1 into the air filter and it fires up, but only runs until it consumes that gas. Then it dies. Repeat, same. It's acting as if it's not getting any gas. Once I opened the gas cap and heard like a vacuum pop. I cleaned the fuel tank vent. But that didn't help. I've filled the tank up, tried to start it up and put it away. The next day, the fuel tank is half empty. No visible leaks around the flippy cap. I dumped the gas and put fresh in, tried to start it, put it away and next day noticed 1/2 tank of gas left. Don't know if that's related to the current problem.

So today, I'll change the impulse line again. It feels a little spongy. The line I bought was sold as impulse/gas line so I would think it's not that. I'll change the fuel tank vent too. And if I have a new fuel filter, that will be replaced.

Any other ideas?