The eGo isnt a 3.7V but you should still be able to get pretty good vapor. Be careful though because your really not supposed to use LR attys/cartos on an eGo. I know plenty of people that do it with no problems, but it does put a lot of stress on the battery. What your really doing is giving yourself very little room for error, so thats why you need to be careful. While I know plenty of people that have never had a problem, I also know alot of people that have fried their mosfet using a LR atty/carto on an eGo.
I also agree with brianishiwa, the first fill is VERY important. I HIGHLY suggest you use a syringe if you arnt now. It will ensure its filled correctly.
I originally posted this for someone who asked how to fill a Ressurector, but this is for really all cartos. Instead of putting the 2ml of juice in a syringe that the Ressurectors hold, youll put the amount of juice the cartos you are using hold.
Heres my copy and paste.
How to fill a cartomizer with a syringe:
"All you have to do is take the dropper part of the bottle off your juice and fill your syringe with 2ml for a new carto. Take the rubber tip off the carto and carefully insert the needle down the side pushing against the metal. DO NOT go thru the filler because it will move it and you could potentially break a connection and your carto. Slide the needle down the side and go all the way to the bottom. Then slowly start dispensing some juice. Dont dispense it all bc then it won't be evenly distributed. Put alittle in, then take it out and insert the needle in a different spot. I normally do it in 3 spots (in a triangle) I found it distributes the best, but you could just do it in 2, on opposite sides. Make sure the needle is at the bOttom bc then you will not have to wait at all for it to settle. Disperse slowly and you will begin to see the toP of the filler become slushy. It is full then, don't put more. If its a new carto is will def hold 2ml, if your refilling it won't take a lot so pay attention and once it gets alittle slushy stop. While your filling hold a napkin or something under the carto bc if you do it too fast a few drops will come out the battery end. If that happens its only bc you did it too fast and the poly fill didn't absorb quick enough.( that happens to me bc I am impatient and fill it in about 10 sec, so I just hold a paper towel or napkin underneath.) wipe up the drops and put the rubber cap back on the carto. Then put the carto between your hands and rub back and forth spinning the carto quickly. This will insure the liquid is evenly distributed in case you put too much on one side from the syringe.
Now you have a perfectly filled ressurector that is ready to be used right away!"
Hope that helps, goodluck!