Edward Rice wrote:

Your 90 psi and low volume is both way overpowered and under volumned
for a sprinkler system. 60 psi is more than adequate to run
sprinkler heads, pressure over that is harmful to fittings.

Yeah -- I cannot run the pump stepped-down, but I can certainly open
two sprinklers at once, so they'd be getting more like 45. Without
the pump, I can't even run one impulse/impact sprinkler reliably,
unfortunately.

What is your pressure without the boosater? My sprinkler pump cycles from 20 psi
to about 35, and works zones with up to 4 impulse sprinklers, 2 - 1/2" and 2 -
3/4". I will suggest that some impulse sprinklers will work, and some won't on
my system. I have had to select by testing. I suspect my 1" PVC piping makes a
bit difference in keeping things working. Pipe pressure drop can make a big
difference.