Mcculloch saw running away

[hairybaby72]

Good day gentlemen, first I would like to say hi and thanks for any help I am about to receive. I have a Mcculloch ms1838av . I picked this up from a friend who said it was not running . It's a very clean saw and doesn't have much use on it. I initially tries to start it and no success. Fuel lines were shot. I replaced all fuel lines gave it a pump and she actually started after some pulls. It would stay running as long as the choke was closed but would take of screaming if you open the choke. At that point I was thinking it is pulling air from somewhere. So i pulled the carb off cleaned it and threw a gasket under it. Still same issue. So I start it again and shoot some carb cleaner around the carb gasket and what I am assuming is the crankcase gasket under the plate that the carb sits on. No response from the crankcase gasket but a small reaction from the carb gasket. Now I'm scratching my head. So I further disassembled the saw and took a peak at the crank seal. It's in one piece and seems to be in relatively good condition. So I have pulled the carb off countless times just to make sure I'm not missing something. I reassemble and now it will start and blubber and maybe stay running if the choke is on. I work on larger engines so i am not highly knowledgeable on saws and I have never seen a carb make a saw scream like it was. Do you think it may have been the carb the whole time causing it to scream and now just blubber? Thanks.

 

[Sagebrush33]

Welcome to the site. Someone with more knowledge then me will be along I'm sure.
I, like yourself, am also used to larger 4-stroke engines.

 

[Hinerman]

@heimannm
@Lee H
@huskihl
@srcarr52

There are many more, but these guys might point you in the right direction.

 

[huskihl]

Maybe the impulse circuit is sucking air? Sounds like there’s definitely a leak somewhere

 

[heimannm]

Can you post a photo of the saw and the carburetor mounting? I think the MS1838 is still the 32/35/38 cc design but was built after Jenn Feng bought the McCulloch name.

Have you tried adjusting the carburetor. Start with both the L and H jets opened around 1-1/2 turns from lightly seated. You will likely need to remove the limiter to be able to adjust the screws as needed.

There should be one gasket between the carburetor and the insulator, and another between the insulator and the cylinder; make sure both are in good condition.

Are you sure the throttle is closing properly?

Mark

 

[hairybaby72]

Can you post a photo of the saw and the carburetor mounting? I think the MS1838 is still the 32/35/38 cc design but was built after Jenn Feng bought the McCulloch name.

Have you tried adjusting the carburetor. Start with both the L and H jets opened around 1-1/2 turns from lightly seated. You will likely need to remove the limiter to be able to adjust the screws as needed.

There should be one gasket between the carburetor and the insulator, and another between the insulator and the cylinder; make sure both are in good condition.

Are you sure the throttle is closing properly?

Mark

Here's a pic I had already . I will upload a better one this evening and one of the mounting. I pulled both the carb and the insulator. Both gaskets were in very good condition. But I actually replaced the carb gasket. I have not tried to adjust the carb at all. The throttle is functioning properly and opens and closes all the way as it should. At first It would just run away as soon as I opened the choke. Now as I have further taken things apart and reassembled it mainly blubbers which is making me lean towards the carb as the issue. I am going to remove the carb and clean it again and adjust the needles and see what happens.

 

[FergusonTO35]

A bit of Permatex number 2 will help carb and base gaskets to seal better. I had the same problem with my Echo CS-400 back when I first got it, wanted to rev to the moon. I took the gaskets off, cleaned everything, dressed it with sealant, and she has been solid ever since.

 

[Nutball]

Did you check how tight the muffler was? If you ended up tightening it in the process of taking things apart, that may be why the lean issue went away. It isn't likely, but an engine can suck fresh air into the exhaust port to cause a really fast lean idle.

 

[hairybaby72]

A bit of Permatex number 2 will help carb and base gaskets to seal better. I had the same problem with my Echo CS-400 back when I first got it, wanted to rev to the moon. I took the gaskets off, cleaned everything, dressed it with sealant, and she has been solid ever since.

Well I'm gonna take the carb off and clean it again and then try this method if sealant.

 

[hairybaby72]

Did you check how tight the muffler was? If you ended up tightening it in the process of taking things apart, that may be why the lean issue went away. It isn't likely, but an engine can suck fresh air into the exhaust port to cause a really fast lean idle.

Muffler was one of the only things I didn't take off but I will check this

 

[hairybaby72]

Here's a pic I had already . I will upload a better one this evening and one of the mounting. I pulled both the carb and the insulator. Both gaskets were in very good condition. But I actually replaced the carb gasket. I have not tried to adjust the carb at all. The throttle is functioning properly and opens and closes all the way as it should. At first It would just run away as soon as I opened the choke. Now as I have further taken things apart and reassembled it mainly blubbers which is making me lean towards the carb as the issue. I am going to remove the carb and clean it again and adjust the needles and see what happens.

Here's some more pics

 

[Sagebrush33]

I'm still here for the education.
That first pic.... your shop's almost as messed up and cluttered as mine.

 

[smokey7]

You sure the throttle idle control throttle stop screw isn't screwed in way too far. And now you have the carb assembled in the wrong order causing the change to a blubber.

 

[hairybaby72]

I'm still here for the education.
That first pic.... your shop's almost as messed up and cluttered as mine.

Lmao. Dude, I just cleaned it!! That's about as good as it gets. Lol

 

[hairybaby72]

You sure the throttle idle control throttle stop screw isn't screwed in way too far. And now you have the carb assembled in the wrong order causing the change to a blubber.

I'm going through it now. I've had quite a few of these apart and chances are it's assembled correctly. But I'm not immune to mistakes so I am definitely going over it again.

 

[Sagebrush33]

Lmao. Dude, I just cleaned it!! That's about as good as it gets. Lol

I used to have a well organized garage that I rented.
Now a days I've got my own and it's a cluttered mess.
I need to spend the time in there and put chit in order.
Part of my problem is I spend a little to much time on OPE.