LAST WEEK I STARTED TO WATER MY YARD AS ALWAYS, AFTER A FEW SECONDS I NOTICED THE SPRINKLER STOPPED BUT I COULD STILL HEAR THE PUMP RUNNING. THEN I NOTICED THE UNION TRANSITION FITTING (WITH RUBBER SEALS TRANSITIONING FROM GALV. PIPE TO PVC) HAD COME APART. I SWITCHED THE BREAKER TO THE OFF POSITION AND REPAIRED THE FITTING. THEN I SWITCHED THE BREAKER BACK ON AND THE PUMP STARTED BUT NO WATER...SO I GOT TWO FEMALE WATER HOSE FITTINGS AND A SHORT PIECE OF HOSE AND PRIMED THE PUMP. IT ONLY RAN FOR A COUPLE OF MINUTES AND THEN NO WATER BUT THE PUMP CONTINUES TO RUN. SO THIS MORNING I REPLACED THE PRESSURE SWITCH AND GOT THE SAME RESULTS. ANY IDEAS ON WHAT MAY BE WRONG ?