Where is the tank vent on a Stihl MS-361?

[cwatkin]

I have a Stihl MS-361 which has been a great saw up until today. I thought the carb was plugged up so I took it off and sprayed it out.

It is running very erratic and like it is starving for fuel, then it runs great, then erratic again. I turned it on its side and ran it with the fuel cap removed and it seemed to run better. I think the tank vent is plugged and causing me to pull a vacuum inside the tank. The saw had sat a while and I guess some varnish could have formed. Where is it located on this saw? What will I have to pull apart to access it?

Thanks,

Conor

 

[old-cat]

There's a little square cap on the right side partly under the front handle where it mounts to the side. Take the handle off first, then pull the cap up.

 

[mortenh]

From the Parts List illustration of the MS 361 tank housing.

"7" is the tank vent (click on the image to magnify)

View attachment 310588

 

[epicklein22]

The tank vent cover falls off quite frequently and that let's the vent clog easily. I'd look into that first. FYI, you shouldn't have to remove the handlebar to change/service the vent.

 

[SawTroll]

The tank vent cover falls off quite frequently and that let's the vent clog easily. I'd look into that first. FYI, you shouldn't have to remove the handlebar to change/service the vent.

That has never happened to me....

 

[old-cat]

The tank vent cover falls off quite frequently and that let's the vent clog easily. I'd look into that first. FYI, you shouldn't have to remove the handlebar to change/service the vent.

My vent cover would fall off and get lost except the handle keeps it there.

 

[SawTroll]

My vent cover would fall off and get lost except the handle keeps it there.

Yes, I don't understand how it could fall off, unless the handle is removed.....

 

[epicklein22]

That has never happened to me....

I use them professionally and have lost 2 on the saws at work and lost one on my personal 361. I've seen other 361's with the cover missing as well.

My vent cover would fall off and get lost except the handle keeps it there.

Yes, I don't understand how it could fall off, unless the handle is removed.....

Look at the IPL, you can see how the vent cover is cut out to allow for handle clearance.....hence no need to remove the handlebar.

 

[cwatkin]

Thanks.

I have some good information on how to proceed. I removed the tank vent and it didn't look nasty or anything but I sprayed some carb cleaner through it in case it was varnished up some. I will see what happens and may just replace it if this doesn't help. Are these something one can clean or do you just replace them?

I may also look into the carb diaphragms as maybe they are worn too but everything points to the vent. I had the jets adjusted out so far just so the saw would stay running. When I pulled the fuel cap off, the saw ran extremely rich and smoky.

Thanks,

Conor

 

[old-cat]

You can take the vent apart, there's a filter inside, leave it out. If that solves the problem, you'll know what you need.

 

[AKDoug]

If you have a vacuum tester you can test it that way too. Apply suction to the fuel line, if it can't build vacuum the vent is fine. The vent is a one-way valve and only vents when suction is applied.

Check the screen in your muffler (if it's still there). It doesn't take much bad running to clog one up. Regardless if that's your issue, you really need to check it at some point since you said you had to run the saw so rich to get it to run.

Tank vents are cheap. Should be right around $6.