One thing I do for the first fill of a new carto in a tank is, after top priming the carto some I leave the top completely off the tank. Then I fill the tank about half way with the bottle then push the top cap down onto the tank. The air pressure from pushing down on the top cap forces a good bit of the juice into the punched holes.
You can repeat if you slide the tank up passed the end of the carto, then remove the top cap. This keeps there from being a suction effect when pulling the top cap off so you don't actually suck juice back out of the carto. Then you just slide the tank all the way back down and push the top cap on again.
I find if I do this until I get a slight gurgle in the carto, then blow out any excess, the carto is completely primed and ready to rock.
Of course, none of the above will help when you start off with a bad carto.