1986 Toyota 4Runner

Coolant seems to be running backwards, it sprays out the radiator cap when turning it over.
I changed the head gasket because it was leaking, changed the thermostat. I did a block presure test and head and gasket are fine, took the thermostat out flushed the radiator. I removed coolant from radiator and turned it over to see if air would push out (it is not). When I put coolant in it is still blowing coolant out the cap. Can water pump impellar be in backwards, the belts are on correct.