What was found
THE CREW HAS BEEN REPORTING DURING APU START THAT IT WOULD HANG AT ABOUT 45% FOR ABOUT 5-6 SECONDS AND THEN LET OUT A LOUD "POP" AND THEN CONTINUE ONTO START AND RUN NORMALLY, NOTE: DURING THE START SEQUENCE IT WAS NOTED A FOG OF FUEL WAS BEING EXPELLED FROM THE APU EXHAUST. TROUBLSHOOTING INCLUDED THE REPLACEMENT OF THE FUEL START NOZZLE AND THE IGNITOR WITH NO CHANGE TO THE START. A FUEL PRESSURE CHECK AT THE START NOZZLE INDICATED A VERY LOW READING (100 PSI) THE ENGINE DRIVEN FUEL PUMP WAS FOUND TO BE DEFECTIVE P/N 4950037 S/N UNK. NOTE: HAMILTON SUNSTRAND T-62T-40C8D1 INSTALLED