Walbro WT-594 Replacement Carb: Extra Brass Tube?

[max2cam]

This Amazon replacement carb for a Walbro WT-594 carburetor on my Echo CS-510 seems identical to the original one EXCEPT for a small brass tube next to the adjustment screws that the original does not have.

What is that tube's purpose? Is it a vent to the atmosphere or what? Should I leave it alone? Or does it connect to something my saw doesn't have and needs to be blocked or capped off?

You can clearly see it on the right hand replacement carb in the attached photo. I wouldn't mess with it, but over the years the original carb has become untuneable in spite of soakings and rebuilds.

Thanks!

 

[max2cam]

Nobody knows what the extra bottom tube on this replacement Walbro WT-594 is for?

Since the original carb doesn't have this tube, my inclination is to block it and see how it runs. If it performs poorly, I can always unblock it. Sure wish I knew it's purpose. Anybody know?

 

[1ofeach]

It's a return line for prime bulb through witch fuel gets sucked in. You will need to plug it in otherwise will leak fuel.

 

[L34]

If your saw doesn't have a primer bulb just blank it off.

 

[max2cam]

It's a return line for prime bulb through witch fuel gets sucked in. You will need to plug it in otherwise will leak fuel.

Thank you! I will plug it.

 

[max2cam]

If your saw doesn't have a primer bulb just blank it off.

Thank you! I will blank it off.

 

[max2cam]

I soldered shut the opening on the extra carb pipe and then covered it with a blob of silicone sealant. Hopefully it will not leak.

This Echo CS-510 comes apart real easily and has been reliable over the past near 20 years. I wonder how the newer Echos compare? I would say my Stihl 026 is a little more powerful, is a slightly better design, but it also uses more gas.