I am pretty sure i don't have any leaks, but there is not enough pressure to push up sprinkler heads and water the entire yard. could my main valve be bad (sprinlers have lost pressure at ever watering station)
If this system is on a well. You might want to check the GPM and see if it has dropped. We are facing this all the time because of dry conditions and low water tables. If this is the case, you can hope that smaller nozzles will solve the problem, or else its a new pump or redisign of the system.