What was found
DURING POST-FLIGHT SECURING OF ACFT, PILOT NOTICED FUEL DRIPPING FROM LT COWL FLAP OPENING. INVEST REVEALED FUEL COMING FROM ENGINE DRAIN LINE TRACED TO THE FUEL INJECTION PUMP. SELECTING THE OFF POSITION OF THE FUEL SELECTOR VALVE RELIEVED THE FUEL TANK HEAD PRESSURE FROM THE SYSTEM AS THIS WOULD CAUSE THE LEAK TO STOP. BEFORE REPLACING THE PUMP, A GROUND RUN WAS PERFORMED TO SEE IF FUEL WAS BEING LOST IN-FLIGHT. NONE WAS OBSERVED. THE PILOT INDICATED THE ENGINE PERFORMED NORMALLY DURING THE LAST FLIGHT, SO THE QUESTION AS TO WHETHER OR NOT AIR WAS BEING DRAWN INTO THE SYSTEM REMAINED UNANSWERED. FUEL INJECTION PUMP REPLACED. (X)