I'm trying to figure out how to keep my pump running (always on) while the sprinklers are running while still having a pressure switch and tank. Can I utilize a pump relay with a pressure switch and how do you connect it?Are you saying that the pressure rises high enough to shut off the 40/60 psi pressure switch, even if the sprinkler system is running? 90 feet of head is only 39 PSI, so I would not expect the pump to shut off while the sprinker is running.
Now if the pump delivers more pressure while the pump is running, maybe adjusting the pressure switch higher would work for you.
So yes, you could switch a relay to convert between using the pressure switch and being always on. But I don't think you would need that.