What was found
TPA - FLT 2636 - AFTER TAKEOFF AT 2,000 FEET AND CLIMBING, THE NR 1 ENGINE START VALVE OPEN LIGHT ILLUMINATED. CREW PERFORMED CHECK LIST PROCEDURES AND LIGHT REMAINED ON. CREW SHUT DOWN THE NR 1 ENGINE AT 5,000 FEET, DECLARED AN EMERGENCY AND RETURNED TO FIELD AT TPA. LIGHT EXTINGUISHED ON BASE LEG. FLIGHT LANDED WITHOUT INCIDENT AND TAXIED TO THE GATE. TOTAL SINGLE ENGINE TIME WAS 10 MINUTES. ALL ENGINE INDICATIONS WERE NORMAL ON TAKEOFF AND BEORE ENGINE SHUTDOWN. MAINTENANCE TROUBLESHOT TO A FAULTY START VALVE. REPLACED NR 1 ENGINE START VALVE. OPERATIONAL CHECK AND LEAK CHECK GOOD. (X)