What was found
AFTER 3RD SORTIE OF THE DAY, AIRCRAFT SAT FOR 45 MINUTES BEFORE NEXT FLIGHT. ENGINE START WAS DIFFICULT USING HOT STARTING PROCEDURES WITH ENGINE RUNNING RPM WAS INCREASING AND DECREASING 200 RPM AND ENGINE OPERATION WAS ROUGH AND ERRATIC. AN ATTEMPT WAS MADE TO PURGE VAPORS IAW LYC''S PROCEDURE WITH NO EFFECT. WHEN THROTTLE WAS RETURNED TO IDLE, ENGINE QUIT. MAINTENANCE ATTEMPTED AN ENGINE START APPROX 15 MINUTES LATER AND WITH MIXTURE FULL OPEN AND BOOST PUMP ON, NO FUEL FLOW INDICATED. ENGINE VAPOR LOCKED. RUN-UP NEXT MORNING NORMAL, NO VAPORIZATION PROBLEMS, SUBSEQUENT TEST FLIGHT SATISFACTORY. MAINT COULD FIND NOTHING DEFECTIVE WHEN ENGINE INSPECTED. (X)