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How to Test a Jet Ski Exhaust Temperature Sensor: Procedures and Tips

Posted by Rod Stewart on

The exhaust temperature sensor in your jet ski is a crucial component that monitors the temperature of the exhaust gases. This information helps the Engine Control Unit (ECU) adjust fuel delivery and ignition timing to ensure optimal performance and prevent engine damage. A malfunctioning exhaust temperature sensor can lead to poor engine performance, increased emissions, and potential damage to the engine. This article will guide you through the procedures for testing a jet ski exhaust temperature sensor.

Tools and Materials Needed

  • Multimeter (with resistance and voltage settings)
  • Service manual (for specific sensor resistance values)
  • Insulated gloves (for safety)
  • Jet ski service stand or stable platform
  • Infrared thermometer (optional but recommended for verifying exhaust temperature)

Understanding the Exhaust Temperature Sensor

The exhaust temperature sensor, also known as the Exhaust Gas Temperature (EGT) sensor, measures the temperature of the exhaust gases exiting the engine. This sensor is typically a thermocouple that produces a small voltage signal proportional to the temperature. The ECU uses this data to adjust the air-fuel mixture and ignition timing for optimal performance.

Step-by-Step Testing Procedure

1. Preparation
  1. Ensure Safety: Make sure the jet ski is on a stable platform or service stand and that the engine is off and cool.
  2. Locate the Sensor: Refer to your jet ski’s service manual to locate the exhaust temperature sensor. It is usually found on the exhaust manifold or exhaust pipe.
  3. Disconnect the Battery: To avoid any electrical hazards, disconnect the battery before starting the testing procedure.
2. Visual Inspection
  1. Check for Damage: Inspect the sensor and its wiring for any visible signs of damage, such as cracks, frayed wires, or corrosion.
  2. Clean the Sensor: If the sensor is dirty, clean it with a suitable electrical contact cleaner.
3. Testing the Sensor with a Multimeter

  1. Set Up the Multimeter: Set your multimeter to measure resistance (ohms).

  2. Test the Sensor Resistance:

    • Refer to the Service Manual: Check your service manual for the expected resistance values at different temperatures.
    • Disconnect the Sensor Connector: Unplug the sensor connector from the harness to isolate it from the ECU and other components.
    • Measure the Resistance: Place the multimeter probes on the sensor terminals (refer to the service manual for the correct pins).

    Expected Readings:

    • The resistance should vary with the temperature. For example, the resistance might be higher at lower temperatures and decrease as the temperature increases.

    Procedure:

    • Record the resistance reading at room temperature.
    • Use an infrared thermometer to measure the exhaust temperature and verify the corresponding resistance value with the service manual.

    Tips:

    • Ensure good contact between the multimeter probes and the sensor terminals.
    • If the resistance does not match the expected values, the sensor may be faulty.
4. Testing the Sensor Voltage Output

  1. Reconnect the Battery: Reconnect the battery and ensure all connections are secure.

  2. Reconnect the Sensor: Plug the sensor back into the harness.

  3. Set Up the Multimeter: Set your multimeter to measure voltage (DC).

  4. Measure the Sensor Voltage:

    • Backprobe the Sensor Connector: Use a backprobe kit to access the connector pins without damaging the wiring. Refer to your service manual for the correct pins (typically, the signal wire and ground).
    • Start the Engine: Turn on the jet ski engine and let it idle.
    • Measure the Voltage: Place the multimeter probes on the backprobed pins.

    Expected Readings:

    • The voltage should increase as the exhaust temperature rises.

    Procedure:

    • Monitor the voltage as the engine warms up.
    • Use an infrared thermometer to verify the exhaust temperature and compare it with the voltage reading.

    Tips:

    • If the voltage reading is outside the expected range, the sensor or its wiring may be faulty.
5. Interpreting the Results

  • Normal Function:

    • The resistance values should vary with the temperature as specified in the service manual.
    • The voltage output should increase as the exhaust temperature rises.

  • Defective Sensor:

    • If the resistance values do not match the expected range or do not change with temperature, the sensor may be faulty.
    • If the voltage output is outside the expected range or does not change with temperature, the sensor or its wiring could be faulty.

Conclusion

Testing the exhaust temperature sensor in your jet ski is a straightforward process that can help ensure optimal engine performance and prevent potential issues. By following the steps outlined above, you can effectively determine the health of your exhaust temperature sensor and make any necessary replacements or repairs. Regular maintenance and testing of your jet ski's sensors can prevent unexpected issues and keep your watercraft running smoothly.

Remember to consult your jet ski's service manual for specific details related to your model, and always prioritize safety when working with electrical components. Keeping your exhaust temperature sensor in good working order is essential for maintaining efficient engine performance and prolonging the life of your jet ski.