Mode I and II (Mixture Feedback Test)

Air/fuel mixture is not adjustable on this engine.
The following procedure will describe inspection of the mixture feedback system.
1. Start the engine and warm it up until the water temperature indicator points to the middle of the gauge.
2. Operate the engine at 2000 rpm for 2 minutes under no load.

Fig. 55 Inspecting E.C.U. Lamps:

3. Make sure that the green L.E.D. on the E.C.U. (located under the R.F. seat) flashes on and off more than 5 times in 10 seconds at 2000 rpm under no load.
a. If OK proceed to step 4. The O2 sensor is operating properly.
b. If not OK, turn the engine off and proceed to step 7.
4. Race the engine 2 or 3 times then idle.

Fig. 52 Selecting Modes:

5. Turn the diagnostic mode selector on the E.C.U. fully clockwise and wait for the L.E.D.`s to flash 2 times, then immediately turn the selector counterclockwise. The ECCS system is now in "Mode 2".
6. Make sure that both L.E.D.'s flash simultaneously.
a. If OK, mixture feedback operation (air/fuel mixture) is correct. Proceed to step 20.
b. If not OK, turn the engine off and proceed to step 16.
7. Disconnect the battery ground cable.
8. Disconnect the ECU 20 pin connector.
9. Disconnect the O2 sensor terminal.

Fig. 148 O2 Sensor Harness Inspection:

10. Using a suitable jumper wire, connect the O2 sensor harness terminal to engine or body ground (not the O2 sensor's wire).
11. Using an ohm meter check for continuity between terminal 19 of the ECU harness and engine or body ground.
a. If continuity does not exist, check the harness for an open circuit and repair or replace harness as necessary.
b. If continuity does exist, proceed to step 12.
12. Reconnect the ECU harness (do not remove the jumper wire at the O2 sensor).
13. Reconnect the battery ground cable.
14. Disconnect the water temperature sensor connector. (Located in the thermostat housing, on top of the engine).
15. Connect a 2.5k ohm resistor to the harness connector.
16. Start and warm the engine to operating temperature.
17. Using an exhaust gas analyzer, check the CO mixture at idle.
a. If CO is between 0.2% and 8.0% replace the O2 sensor and proceed to step 1.
b. If CO is not between 0.2% and 8.0% proceed to step 18.
18. Remove the resistor from the water temperature sensor and reconnect the connector.
19. The mixture feedback system is faulty. Perform MODE 3 (STORED CODES) TEST and repair any faults. Also check fuel pressure in FUEL SYSTEMS and repair any faults found.
20. Turn the engine off. Turning the engine off will return the ECCS system to Mode 1 (normal operating mode).