2004-2005 Kawasaki STX-15F Jet Ski Factory Service Manual., Page 101Get this manual
FUEL SYSTEM (DFI) 3-53 Ignition Coils (Service CodeCharacter-51, 52COL1, COL2)
Ignition Coil #1, #4: Service Code 51-COL1 Ignition Coil #2, #3: Service Code 52-COL2
Ignition Coil RemovalInstallation CAUTION
Never drop the ignition coils, especially on hard surfaceSuch shock to the ignition coil can damage it
See Ignition System section in Electrical System chapterInput Voltage Inspection
Be sure the battery is fully charged