Soldering iron. Seriously, take the fairing off, put it together and make a few melts parpendicular to the crack from the inside, every inch or so. then fill in the line.
If you can get ahold of a plastic welder (which is a hot air gun that feeds tubes of plastic, like a tig welder) its even easier.
Plastic welds will not have the strength of the original piece, but it will look nice, and will be stronger than crazy glue.