Chevrolet Light Duty Truck 1973, Service Manual

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6 T - 3 4 E M I S S I O N C O N T R O L S Y S T E M S
• Connect the hoses at the pump.
• Tighten mounting bolts securely.
Pressure Relief Valve
NOTE: The pressure relief valve is incorpo­
rated in the diverter valve. The complete unit
must be replaced to correct a malfunction of
the relief valve.
DIAGNOSIS
While the A.I.R. system will result in exhaust emissions
below the requirements when it is properly installed and
maintained, it will not provide the desired reduction in
exhaust emissions if some of the engine components
malfunction.
Because of the relationship between “Engine Tune Up”
and “Unburned Exhaust Gases”, the condition of Engine
Tune Up should be checked whenever the Air Injection
Reactor System seems to be malfunctioning. Particular
care should be taken in checking items that affect the
fuel-air ratio such as the crankcase ventilation system,
the carburetor and the carburetor air cleaner.
If all other components seem to be operating
satisfactorily, visually inspect A.I.R. system for loose
drive belts, loose or deteriorated hoses and missing or
broken components.
If after completion of tune-up and visual inspection,
malfunction still exists, refer to the diagnosis chart for
symptons, probable cause, and remedy.
NOTE: The A.I.R. system is not completely
noiseless. Under normal conditions, noise
rises in pitch as engine speed increases. To
determine if excessive noise is the fault of the
air injection system, disconnect the drive belt
and operate the engine. If noise now does not
exist, proceed with diagnosis.
LIGHT DUTY TRUCK SERVICE MANUAL