System Testing
1981-82 3A-C Engine1. Check hoses and tubes for loose connections, cracks, kinks, or damage. Repair or replace as necessary.
2. Disconnect air by-pass hose from air cleaner.
3. Start engine. With coolant temperature below 46° F, air should be discharged from air by-pass hose.
4. Warm up engine to between 53° and 127° F. Air should not be discharged from by-pass hose with engine at approximately 2000 RPM.
5. Warm up engine until it reaches normal operating temperature. Air should be intermittently discharged from by-pass hose with engine at approximately 2000 RPM.
6. Air should not be discharged from by-pass hose with engine at idle.
7. With engine at idle, disconnect air switching valve vacuum hose. Air should be discharged from by-pass hose.
8. Reconnect hose to air switching valve. Air discharge should cease within 2 to 6 seconds.
9. With engine idling, disconnect hose from air by-pass valve. Air should not be discharged from by-pass hose.
10. Reconnect hose to air by-pass valve. Air should be momentarily discharged from by-pass hose.
11. With engine at idle, pinch off vacuum hose to vacuum switch.
12. Gradually increase engine speed. Intermittent discharge from by-pass hose should stop above 1600 RPM.
13. Release pinched hose.
14. With engine idling, short two bottom terminals of service connector. Air should be discharged from by-pass hose. Disconnect short.
15. With engine idling, disconnect hose between check valve and EGR valve at check valve side. Air should be discharged from check valve. Reconnect hose to check valve.
16. If test results are not as described, test components individually.
1981-82 3T-C Engine
1. Check hoses and tubes for loose connections, kinks, cracks, or damage. Repair or replace as necessary.
2. Disconnect hose between vacuum control valve for evaporative emission system and vacuum connector at connector side and plug connector.
3. On vehicles equipped with high altitude emission control system, disconnect vacuum hose between high altitude control valve and check valve at check valve side and plug check valve.
4. Disconnect air by-pass hose from air cleaner, then start engine.
5. With crankcase temperature below 46° F, air should be discharged from by-pass hose.
6. With crankcase temperature above 66° F, and coolant temperature below 109° F, air should not be discharged with engine above 1290 RPM for 1981 except California, above 1590 RPM for 1981 California, or at idle for 1982.
7. Warm up engine until it reaches normal operating temperature. Air should be intermittently discharged from by-pass hose at 2000 RPM but not at idle.
8. Race engine and quickly close throttle valve. Air should be momentarily discharged from by-pass hose.
9. With engine idling, disconnect vacuum hose between vacuum transmitting valve and 3-way connector at valve side. Air should be discharged from by-pass hose within 15 to 25 seconds for green vacuum transmitting valves, 30 to 55 seconds for red valves, or 50 to 90 seconds for pink valves.
10. Reconnect hose to vacuum transmitting valve. Air discharge should cease after a few seconds.
11. With engine idling, short top two terminals of service connector. Air should be discharged from by-pass hose. Disconnect short.
12. Pinch off hose to vacuum switch at idle and slowly increase engine speed. Intermittent air discharge should cease above 2200 RPM. Release pinched hose and reconnect all hoses.
13. If test results are not as described, test components individually.
1981-82 22R Engine
1. Check hoses and tubes for loose connections, cracks, kinks, or damage. Repair or replace as necessary.
2. Disconnect air by-pass hose from air cleaner.
3. On vehicles equipped with high altitude control system, disconnect vacuum hose from lower port of high altitude control valve and plug end of hose.
4. With coolant temperature below 43° F, start engine. Air should be discharged from air by-pass hose.
5. With coolant temperature between 64° and 109° F, air should not be discharged from by-pass hose with engine at idle.
6. Disconnect vacuum hose between check valve and vacuum pipe at check valve and plug end of hose. Air should not be discharged from by-pass hose. Reconnect hose.
7. Warm up engine until it reaches normal operating temperature. Air should be intermittently discharged from by-pass hose at 2000 RPM.
8. Race engine and quickly close throttle valve. Except on Cab & Chassis models, air should he momentarily discharged from by-pass hose.
9. With engine idling, short top two terminals of service connector. Air discharge from by-pass hose should now be continuous. Disconnect short.
10. If test results are not as described, test components individually.