Symptom Related Diagnostic Procedures

NOTE: The Air Injection Reactor (AIR) system is not completely noiseless. Under normal operating conditions, noise increases as engine speed increases. To determine if the system is faulty, remove drive belt and operate engine. If there is no noise, proceed as follows:

Excessive Belt Noise
1. Loose air pump drive belt. Tighten drive belt to specification.
2. Seized air pump or drive belt excessively tight. Replace air pump.

Excessive Pump Noise, Chirping, Rumbling Or Knocking
1. Insufficient pump break-in period. Operate vehicle to allow a sufficient break-in period.
2. Loose air pump hose. Tighten or replace hose clamp.
3. Leaking air pump hose. Locate leak and replace hose.
4. Air pump hose contacting other engine component. Adjust hose position.
5. Diverter valve inoperative. Replace diverter valve.
6. Check valve inoperative. Replace check valve.
7. Loose air pump mounting fasteners. Torque mounting fasteners to specification.
8. Air pump inoperative. Replace air pump.

No Air Supply
1. Refer to step 2.
2. If air is expelled through diverter muffler with engine at idle, replace diverter valve.
3. Check valve inoperative. Blow air through hose toward air manifold. If air passes through, check valve is operating properly. If air can be sucked away from manifold, replace check valve.
4. Air pump pressure relief valve leaking or damaged. Replace pressure relief valve.

Centrifugal Filter Fan Damaged Or Exhaust Tube Damaged
1. Replace centrifugal filter fan.
2. Relace exhaust tube.

Backfire In Exhaust System
1. Inoperative or incorrectly adjusted choke. Check choke operation and correct as necessary.
2. Inoperative vacuum break. Replace vacuum break.
3. If vehicle incorporates a manual choke, check for overchoking. Adjust choking control period.
4. Dirty or damaged air cleaner element. Replace air cleaner element.
5. Improper crankcase ventilation. Check system and replace PCV valve, if necessary.
6. High fuel level. Adjust carburetor float level.
7. Diverter valve stuck in open position. Check valve and replace, if necessary.
8. Diverter valve and distributor timing vacuum lines switched. Correct hose routing.
9. Vacuum switch valve stuck in closed position or vacuum switch filter plugged. Check and replace vacuum switch valve, if necessary.

Backfire Or Popping In Inlet Manifold
1. Leaking inlet manifold. Check manifold bolts for tightness, torque bolts to specification.
2. Incorrect ignition timing. Check timing.

Off Idle Hesitation Or Rough Idle (hot)
1. Disconnected, split or oversized vacuum hoses. Check hoses and replace, if necessary.
2. Hot idle compensator not closing or opening prematurely. Plug carburetor hot idle compensator port in air horn. If this corrects the condition, replace hot idle compensator.
3. Insufficient fuel supply to combustion chamber, or fuel leaking past accelerator pump seal during pump travel. Check accelerator pump adjustment. If rubber seal is falls into pump cavity by its own weight (with return spring removed), replace accelerator pump seal.
4. Carburetor float level low. Adjust as required.
5. Incorrect ignition timing. Check timing and adjust to specification.

Rough Idle Or Surge
1. Incorrect carburetor adjustments. Check carburetion and adjust as required.
2. Incorrect ignition timing. Check timing and adjust to specification.
3. Vacuum leak at signal line to diverter valve or distributor. Check and correct vacuum lines and connections.
4. Vacuum leak at carburetor or intake manifold. Check for leaks at carburetor and intake manifold gaskets. Replace gaskets, if necessary.

Overheated Exhaust System
1. Incorrect ignition timing. Check timing and adjust, if necessary.
2. Missing pressure relief valve plug on air pump. Check for plug and install plug, if necessary.

Damaged Air Supply Hose
- Defective Check Valves, Replace Check Valve As Required

Constant Air Noise
1. Damaged air hose. Replace hose.
2. Diverter valve stuck closed. Replace diverter valve.