Someone advised me that [the air temperature sensor] is under the air cleaner box.
The air temperature sensor is mounted to the air silencer. Most outboard engines do not have an air cleaner because on the water there is very little dust or other solid particulate in the air stream, unlike on land where road dirt could be in the air stream.
- ETEC_150_AirTemperatureSensor.jpg (22.11 KiB) Viewed 4806 times
It seems odd that a simple, passive resistor sensor would go bad. I would check the electrical connections to the air sensor now in the engine before replacing it. If there is a discontinuity in the electrical connections, the E-TEC EMM might give you a diagnostic about the air temperature value out of range. Please indicate the exact nature of the diagnostic message. Did you obtain a FAULT CODE number? It should be in the range of 47-48-49.
It would be more common to discover that some corrosion had developed on the electrical contacts of the connection between the air temperature sensor on your E-TEC and the wiring harness that carries the signal to the EMM, than to discover that the sensor completely failed.
Here are a few excerpts from the service manual that may be useful for you:
Air Temperature Sensor
The air temperature sensor monitors the air temperature at the throttle body.
Air Temperature Sensor (AT) Test
Remove the electrical connector from the air temperature sensor. Use a digital multimeter to measure sensor resistance.
AT Sensor Resistance
680 Ω ± 5.25% @ 212°F (100°C)
10000 Ω ± 1.5% @ 77°F (25°C)
32654 Ω ± 3.0% @ 32°F (0°C)
Measure the resistance of the air temperature sensor at an ambient air temp around 77-degrees-F. The resistance should be as shown above.
If you do need to replace the sensor, then as far as I can tell from browsing the service manual, there is no particular special procedure for replacement. Remove the wire connector from the old sensor; removed old sensor from air silencer; install new sensor onto air silencer; install wire connector.