What happens if I run saw without tank vent valve (MS250)

[MMFoF]

Hi, I know that's a dumb question in the sense that I should just run it with the proper part. But I have ordered one and am waiting for it to arrive, and am wondering what would happen if I tried to run the saw without it? I know the idea is to let air in and not out, but I thought that would be to provide atmospheric pressure and avoid a vacuum build up in the tank. So what happens if there is no valve there? There would be no vacuum build-up, but what's the down side - would I have fuel spewing out of the hole where the vent is supposed to connect to?
Thanks

 

[Mad Professor]

Hi, I know that's a dumb question in the sense that I should just run it with the proper part. But I have ordered one and am waiting for it to arrive, and am wondering what would happen if I tried to run the saw without it? I know the idea is to let air in and not out, but I thought that would be to provide atmospheric pressure and avoid a vacuum build up in the tank. So what happens if there is no valve there? There would be no vacuum build-up, but what's the down side - would I have fuel spewing out of the hole where the vent is supposed to connect to?
Thanks

Yes. Not sure if you can rig up a vent using fuel line and grub screws like Stihl did with it's older saws.

 

[ballisticdoughnut]

It will leak fuel if rotated clutch side up but other than that it will run fine.

 

[cscltd]

Fuel leaking out would be first problem-second would be dirt getting into tank
So best to replace it

 

[Mad Professor]

It will leak fuel if rotated clutch side up but other than that it will run fine.

Fire hazard too