I ask, because I didn't this last time. My JetLite wouldn't light, the view window showed nothing, and I just went ahead and injected it. About 5secs at a crack, for 3-4x until the window was full. My el-cheapo back-up has no window, but I went ahead and filled it likewise. How many "lights" am I actually really giving up by not purging it several times until it will hiss out no more fuel? It no longer seems worth it to me.