Suzuki Outboard Stalls/Stalling or Runs Rough

When a Suzuki outboard motor stops running because of an overload on the engine, or begins to operate irregular, then follow these simple troubleshooting steps to pinpoint the cause of the problem. For reference, these repair instructions pertain to certain electronic fuel injection Suzuki outboard motors experiencing the following scenario:

• Unstable idling
• Engine tends to stall
• Engine stalls when put into gear
• Outboard stalls when accelerating
• Outboard stalls at full throttle
• Outboard stalls at idle

Before you begin to troubleshoot the motor, ensure there is no self-diagnostic code indication. Also, download the service manual for your exact model, you’ll need it.

Turn the ignition switch “ON”. Use a voltmeter to check terminal voltage. Refer to service manual for which terminal number to check (e.g. terminal C8 or D8), and to check the correct voltage specifications. If terminal voltage test good for both terminals, the possible causes could be:

• Incorrect by-pass air screw adjustment
• IAC (Idle Air Control) valve failure
• IAC passage failure (check for a clogged hose, silencer, etc.)
• Spark plug failure (check heat range, broken insulator or worn plug(s)
• Ignition coil failure (test coil)
• ECM (engine control module) failure
• Wire continuity / connection failure
• Possible failure of high pressure fuel system components:
  • Fuel injector (blockage, stuck or leaking valve, etc.)
  • Fuel pressure regulator (incorrect fuel pressure, etc.)
  • Fuel pump (leakage in fuel tank, blockage of suction filter, etc.)
  • Fuel filter (contamination, clogged, etc.)
  • Hose (bend or kink, blockage, clogged, etc.)

For reference, if the neutral switch is malfunctioning or has failed, the motor will usually stall when shifting the engine into gear. Moreover, if the neutral switch has malfunctioned as “always ON”, the motor will fall into limp mode (engine speed is limited to 3000 r/min by intermittent fuel injection and ignition timing will also be fixed).

If the idle air control valve failed, the engine’s “fast-idle function, which is used to warm-up the motor, will no longer operate. If the CTP switch/sensor malfunctioned, the outboard motor will tend to stall when the engine is decelerating.

If voltage at terminals is always 0 V (zero volts), check the natural switch function and CTP switch/sensor function. If both test good, it indicates possible ECM failure. If voltage at the terminals did not test good (e.g. always 5 V or below factory specifications), it indicates possible neutral switch failure or CTP switch/sensor failure.