CO Test

Fig. 15 Connecting CO meter & service connector No. 5151 to engine:

1. Connect a suitable CO meter, tachometer and service connector No. 5151, Fig. 15, to engine. Ensure connector lever is in mid-range position.
2. Start engine and disconnect hose from pressure differential switch. Place a finger over hose end. No suction should be felt, indicating that the thermal vacuum switch is closed.
3. Allow engine to reach normal operating temperature.
4. Check idle speed and CO content. Idle speed should be 750 RPM with air conditioning off. If not, correct idle speed to specification. CO content should be 0.7-1.3%. If not, refer to ``CO Adjust.''