What was found
APU WILL NOT START. HANGS BETWEEN 25 & 35 PERCENT RPM & SHUTS DOWN WITH FAULT LIGHT ON. ATTEMPTED 3 STARTS. 1ST START APU STARTED UP NORMAL. 2ND START APU START VERY SLOW & STARTED TO HANG AT 35 PERCENT. 3RD ATTEMPT APU HAD A HUNG START & FAULTED. EGT NORMAL ON ALL ATTEMPTS. SUSPECT STARTER FAILING. REPLACED STARTER. REPLACED FCU, IGV ACTUATOR & INLET PRESSURE SENSOR, APU STARTS ONCE & HAS HANG STARTS 2 ND AND 3 RD TIME. NO FAULTS WITH ECU, EGT INCREASES NORMAL & HANGS BETWEEN 25-35 PERCENT. FOUND "APU FAULT" DISPLAYED. REPLACED ECU, NO HELP. REINSTALLED ORIGINAL. CONTINUED T-S. REPLACED BATTERY & CHARGER. SUCCESSFULLY STARTED APU SEVERAL TIMES. NO DEFECTS NOTED.