Paint peeling off pretty easy... how far to chase?

[hotwls13]

I'm not planning on taking this truck down to the metal for repaint. I'm either doing rattle can or single stage.

Current paint is rough with a few good areas. On the drivers door, surface rust in one area and there is no paint in that area. Next to it is chipping white paint. If I chip away at the chipping/lifting paint i can get it off in 2" chunks. Chips look they are paint with primer underneath. Then primer remains on the truck surface. My guess is the truck was primered at some point, then they came along and sprayed a different and paint that didn't stick properly. That make sense??

SO my question is, is just scraping off the loose stuff, taking off anything that comes off easily good enough? Then I can feather in the edges, scuff the rest and repaint??

I'm guessing the painters are gonna say get rid of it all and start over. Just don't have the time or $$ for that.

Thoughts?