I know the term "overflow" is probably incorrect, but it's 4:30 a.m. and I haven't had my first cup of coffee yet...
This is the little tube that drains any surplus fuel from the injector. On the original British CS/6 engines, I believe a small cup was placed under the end to collect fuel that leaked from the injector. On my Vidhata, the line was simply plumbed into the fuel line from the tank. I replaced the tank with a better one and just left the line hanging loose.
The engine has about 20 hrs. total on it since new and runs fine, but I haven't seen one drop of fuel come out of that line. Is this normal, or should I be looking for a potential problem?