Ms 310 shooting gas out of breather hose help

[GMB74]

The IPL I pulled up does indeed show the old style hose and grub screw setup.
They do sometimes leak gas under the right conditions.
I have had better luck with the little white Echo style valves.

 

[stihltech]

Maybe right at the changeover.
Look above onr the plastic cylinder shroud. You should see a pocket part way up. The end of the hose with the 2 grub screws fits in it on the original style. It keeps the hose end from vibrating around. That vibration will cause fuel to exit the end of the vent and leak.
Sounds strange, but I have fixed a few by putting the hose in this pocket.

 

[a. palmer jr.]

Here’s the lines the breather and the Line to the tank are both new.but I did screw the screw in the vent line didn’t know I wasn’t supposed to. The line in question is the top fuel and air bubbles come out of there.

I usually just run a hose in it's place with an Echo mushroom breather on it's end. The grub screws eventually get the hose stopped up so I never use them.

 

[ZeroJunk]

I don't care if they leak.

 

[stihltech]

The lengths we go on here to fix a non issue.
When the hose with the two grub screws is installed correctly in the holder on the cylinder cover, there is only any leakage if you turned the saw upside down. This is how you can check for a clogged old style vent.
When it is free to vibrate, it is amazing how much fuel will come out. Common repair on these saws. Easy and cheap.
In an earlier statement, I forgot the difference between the flat top MS290,310 and 390 series that was out for a short time. When the changed to the more rounded top and filter cover, so did the vent (to the best of my recollection).
Either way, just put it back to original.
And do not screw the grub screws into the hose. That will make threads inside the hose which will plug up. PUSH the screws into the hose.