Pontiac FIREBIRD 1972 Service Manual page 758

EMISSION CONTROL SYSTEMS 6D- 15
.-
CON NECTION 'DIAPHRAGM
ASSEMBLY
Fig. 6D-23 Diverter Valve (Typical)
On engine decelleration the total air supply is dumped
through the muffler on the diverter valve. At high engine
speeds the excess air is dumped through the pressure relief
valve which is incorporated in the diverter valve.
The check valve prevents exhaust gases from entering and
damaging the air injection pump, as back flow can occur
even under normal operating conditions.
When properly installed and maintained, the A.I.R. Sys-
tem will effectively reduce exhaust emissions. However, if
any A.I.R. component or any engine component that op-
erates in conjunction with the A.I.R. System should mal-
function, the exhaust emissions might be increased.
Because of the relationship between "Engine Tune UP"
and "Unburned Exhaust Gases", the condition of the En-
gine Tune Up should be checked whenever the A.I.R.
System seems to be malfunctioning. Particular care should
be taken in checking items that affect fuel-air ratio such
as the crankcase ventilation system, the carburetor and
the carburetor air cleaner.
Because of the similarity of many parts, typical illustra-
tions and procedures are used except where specific illus-
trations or procedures are necessary to clarify the
operation.
MINOR SERVICE
DRIVE BELT
INSPECTION
1. Inspect drive belt for wear, cracks or deterioration
and replace if required.
Fig. 6D-24 Checking A.I.R. Pump Belt Tension
2. Inspect belt tension and adjust if below 70 lbs. using
a belt tension gauge.
ADJUSTMENT
Loosen pump mounting bolt and pump adjustment
bracket bolt. Move pump until belt is properly tensioned
then tighten adjustment bracket bolt and mounting bolt.
Use a belt tension gauge to check adjustment (Fig. 6D-24).
CAUTION:
Do not pry on the pump housing.
Distortion of the housing will result in exten-
sive damage to the Air Injection Pump.
REPLACE
1. Loosen pump mounting bolt and pump adjustment
bracket bolt then swing pump until drive belt may be
removed.
2. Install a new drive belt and adjust as outlined above.
PUMP PULLEY
REMOVE
1. Hold pump pulley from turning by compressing drive
belt then loosen pump pulley bolts.
2. Remove drive belt as outlined above then remove
pump pulley.