Oxygen Sensor: Testing and Inspection

Fig. 77 Engine Check Connector:

1. Start engine and warm-up to normal operating temperature.
2. Locate the engine check connector near the clutch reservoir and connect a voltmeter to the check connector. Fig. 77
3. Connect the positive (+) probe to terminal Ox and the negative (-) probe to E1.
4. Maintain engine speed at 2,500 rpm for 90 seconds.
5. After step 4, check the number of times the voltmeter oscillates between 0 and 6 volts. There should be 8 or more oscillations in a 10 second duration.
6. If not as specified, check the oxygen sensor wiring circuit for shorts or opens.
7. If no problems are found with the circuit, replace the oxygen sensor.
8. After replacement, repeat steps 1 - 5.
9. If zero oscillations occur, replace the carburetor feedback ECU.