(for a: 1990 Chevy g20 v8 5.7l)

Started bleeding brakes but fluid was blasting out of the reservoir when I depressed the pedal.
So today I replaced the Master Cylinder with a new one. Did a rigorous (i think) bench bleed before installing the new one.
It's still doing it.
Tomorrow I plan on bleeding the other three brakes. read that air in the lines could cause this too. I have reason to believe that air may have gotten into the rear brake lines.
Wondering if i'm on the right track or maybe there's more to consider. Any advice would be highly appreciated. thanks

 

would not condemn it at this point. put the cap on....bleed the brakes. if you have proportioning valve...open it or the rear won't move fluid. when done do a abs auto bleed with the scan tool.

 

Well you are supposed to keep the M/C cap on loose,. not take it off.That way you get all the air out. I'd not leave that fluid long on ypour car or it will damage the paint. Get it bled out and wash the fluid off.

 

With the cover even slightly off fluid still goes everywhere.
yeah brake fluid is corrosive stuff. The van is going in for a full paint job in a couple months so not worried about that too much. I just wiped it down.
But do you think full bleeding will solve this?