Test 10 EGO Always Rich (Code 42)

Fig.8 - MCU System Wiring Circuit:

1. Make sure that engine coolant is at normal operating temperature.

2. Disconnect jumper wire from Self-Test Trigger input circuits 201 and 60, Fig. 8.

3. Make sure that there is power to the choke cap, cold enrichment circuit is operating and that choke is off.

4. Disconnect Thermactor air hose at pump.

5. Disconnect vehicle harness from EGO sensor.

6. Connect a voltmeter between EGO sensor and engine block ground.

7. Disconnect PCV hose from carburetor to create a vacuum leak, then run engine at 1800 rpm for 60 seconds while observing voltmeter. If voltage at .50 volts or less, reconnect PCV hose, EGO sensor to harness and proceed to next step. If voltage is greater than .50 volts, replace EGO sensor.

8. Disconnect vehicle harness from FBCA motor, then connect a known good FBCA motor with pintle fully depressed to harness, but do not remove original FBCA motor from carburetor.

9. Turn ignition key to run position.

10. Apply 10-12 inches Hg vacuum to zone vacuum switches.

11. Start engine and place on high cam. Wait 120 seconds, then create a rich condition by depressing CVR rod while observing remote FBCA motor shaft. If shaft retracts until flush with motor, turn key off, reconnect Thermactor air hose to pump and proceed to Test 11-FBCA Motor. If shaft does not retract, disconnect known good FBCA motor from harness and proceed to Test 7-FBCA Motor Harness Check.