I can’t respond to specifically about outboards but looking at my parts motors that have been resprayed. They seem to delaminate and chip away leaving the original coating. Adhesion is a vital part of any coating. The outboards I have are 50-55 years old and were soaked in oil their entire life. In addition Evinrude and Johnson had identical parts that were coated with different colors and that may be one reason. Salt exposure to uncoated material (parts) is a place you’d want to get under all of the oxidation and aluminum oxidation is not apparent.
Just my 2 cents, hopefully someone with more direct experience will chime in.
