Excessive Carbon Monoxide (CO), Caused By Rich Mixture

1. Engine not at normal operating temperature.
2. Improper idle mixture.
3. Sticking or improperly adjusted choke.
4. Lead contamination of catalytic converter.
a. Check for absence of fuel tank filler neck restricter.
5. Improperly operating pulse air or secondary air system.
6. Leaking carburetor fuel passages or gaskets.
7. Incorrect carburetor float level.
8. Restricted air cleaner element.
9. Faulty feedback system.
10. Leaking carburetor fuel passages or gaskets.