1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 91Get this manual
ENGINE CONTROL SYSTEM 3-36 NOTE1: Disconnect remote control wire harness, and connect tester probe to terminal (Gray wire)
OTHER INSPECTION
FUEL INJECTOR OPERATING SOUND (CRANKING) (1) Touch sound scope or long blade screw driver to fuel injector body as shown(2) Crank engine and check for injector operating soundInjector operating sound"Click"
FUEL INJECTOR OPERATING SOUND (INDIVIDUAL) (1) Disconnect fuel injector wire, and connect the test cord09930-89260Injector test cord (2) Connect Gray wire to body ground(3) Momentarily touch BlackYellow wire to starter motor relay right terminal (connected to battery positive (+) terminal), and check for injector operating soundInjector operating sound"Click"