Carbureted Engines

On 1986-87 Federal and High Altitude CRX HF, refer to Troubleshooting for system self-diagnosis procedures.

Cold Engine

1. Engine coolant temperature must be below set temperature of thermosensor and thermosensor must have continuity.
2. Disconnect vacuum hose from EGR valve and connect vacuum gauge to hose.
3. Start engine and raise engine speed to 4500-5000 RPM.
4. If vacuum is not available, proceed to hot engine inspection.
5. If there is vacuum, replace thermovalve C and check for voltage at EGR control solenoid valve.
6. If there is voltage, replace EGR control solenoid valve and retest.
7. If there is no voltage, check thermosensor operation, wiring, and fuses, repair or replace as necessary and retest.

Fig. 64 Vacuum & Voltage Chart.:

Hot Engine

1. Disconnect vacuum hose from EGR valve and connect vacuum gauge to hose.
2. Push voltmeter positive probe into yellow/white (1985-87 Civic 1300), brown/black (CRX HF) or gray (1985-87 Civic 1500 and CRX Std.) wire terminal control box connector and connect negative probe to suitable ground.
3. Raise and support front of vehicle, block rear wheels, and apply hand brake.
4. Start engine and allow it to reach normal operating temperature.
5. Check that vacuum and voltage appear as indicated in appropriate chart,Fig. 64.
6. If readings are incorrect, refer to appropriate troubleshooting procedure.