Yup. Take the bleeder screws OUT and clean them. They plug with dirt (very common.)
The hole in the caliper that fluid flows out of may also be plugged with crap. Any restriction anywhere in the system will reduce fluid flow.
I cheat: AFTER cleaning the bleeder screw with a small drill bit turned by hand, I put the screw in the caliper, put a hose on the screw to direct the fluid...then with the pressure bleeder connected to the master cylinder, and the other bleeder screws closed, STOMP on the brake pedal to force the "clots" out. Repeat as needed for any wheel cylinder/caliper that won't flow properly.
If the hose pops off the bleeder screw, you'll have fluid squirting all over.
I tend to use ~15 psi on my pressure bleeder, fluid shoots out the bleeder screw when everything is working properly.