i've painted many parts for jet skis. the first method just using krylon fusion/rustoleum paint for plastics wasnt too sucessful. simply cleaned parts and painted. didnt last long. covers left imprints in paint, scratched off, ect.
my 2nd method was sucessful and looked professional.
clean parts with paint thinner, degreaser, or just soap and water. wet sand with 400 grit, wash with soapy water, let dry in sun, use rustolem primer for plastics. put a nice coat that covers the whole piece, wetsand with 600, recoar and re wet sand with 600 until you get a smooth finish. wet sand it good, like try to take the primer off. if it comes off, then paint would have too. after you get it primed, use regular spray paint, i prefer plastikote. any paint will work after its primed good. do the same process, paint, wet sand with 600, paint wet sand with 600 until you get a finish you like. when it looks good, stop!
i've done some pretty amazing hoods on pwcs this way, people cant believe it was done with a rattle can