What was found
ON INITIAL CLIMB, THE PILOT REPORTED FUEL FLOW OF 160PPH. AFTER REACHING CRUISING ALTITUDE THE FUEL FLOW WENT TO 0 & THE PILOT REPORTED TEMP POWER LOSS. THE PILOT WENT THROUGH THE ENG FAILURE CHECKLIST & PLACED THE AUXILIARY BOOST PUMP ON IN THE HIGH SETTING. THE FUEL FLOW WENT TO 170PPH, BUT THE PILOT REPORTED THERE WAS STILL A POWER LOSS. THE PILOT THEN PLACED THE AUXILIARY PUMP IN LOW & THE ENG REGAINED NORMAL POWER INDICATIONS & PERFORMANCE. THE PILOT RETURNED TO DEPARTURE AIRPORT. MAINTENANCE INSPECTED THE ACFT & REPLACED THE RT ENG FUEL FLOW TRANSDUCER IAW THE SIM & SET UP THE RT ENG FUEL FLOW IAW MM 73-20-01. THE ACFT WAS RUN WITH NO DEFECTS OR POWER REDUCTION NOTED. BASED ON THE PILOTS REPORT & MAINTENANCE FINDING THE POWER LOSS WAS LIKELY DUE TO THE AUXILIARY PUMP PLACED ON HIGH CAUSING TOO RICH MIXTURE.