Sounds like you do not have the painted thinned down enough....

When I was a kid I "primed" my 41 chevy in my parents car port... Primer was almost dry when it hit the metal and tip kept plugging up.. I was using straight primer with NO thinner.. LOL

Guy who traded me his 69 A12 super bee for it was a body guy.. Called the primer on the coupe "Rhino Hyde"....