What was found
AFTER PUSHBACK, UNABLE TO START #1 ENGINE. AFTER START LEVER WAS RAISED TO IDLE, WE HAD NO ENGINE IGNITION. FUEL FLOW WAS NORMAL. A 2ND START ATTEMPT WAS MADE BUT WAS NOT SUCCESSFUL. IGNITION SWITCH WAS ON THE LEFT SIDE. GROUNDED - YES. TROUBLESHOT #1 ENGINE LEFT IGNITION PER B737-900 FIM TASK 74-21. SUSPECT LEFT MAIN IGNITER & EXCITER FOR DEFECT. REMOVED & REPLACED LEFT IGNITER PLUG W/ NEW, OPS CHECK GOOD, PER B737-900 AMM 74-21-02. REMOVED & REPLACED LEFT IGNITER EXCITER W/ NEW, OPS CHECK GOOD, PER AMM 74-11-01. IGNITION AUDIBLE TEST GOOD PER AMM 74-00-00.