Accord and Prelude 1800 (Calif. Man. Trans.)
- Begin test with cold engine. Connect a vacuum gauge to vacuum hose at Retard side of distributor vacuum unit. Start engine. No vacuum should be present.
- If vacuum is present, check for battery voltage at Blue/Yellow wire at purge control/unloader solenoid valve. If voltage is present, replace valve. If no voltage, check for continuity between Black/Yellow and Yellow wires at thermosensor connector. If no continuity, replace thermosensor. If continuity, check fuse and wiring.
- Connect vacuum gauge to hose at Advance side of distributor mechanism and start engine. Vacuum should be present at 3500 RPM. If not, check for vacuum to delay valve. If vacuum is present, replace delay valve. If not, inspect check valve and carburetor port.
- Allow engine to warm up and check for vacuum at Retard hose. If no vacuum, check for continuity between Black/Yellow and Yellow wires at thermosensor. If no continuity is present, sensor is okay. If continuity is present, replace sensor.
- Reconnect sensor wiring and check for battery voltage at Green wire by probing back of connector. If voltage is present, replace vacuum switch. If no voltage and still no vacuum at Retard hose, check for blocked vacuum port or plugged ignition solenoid valve. Repair and recheck.
- Leave gauge connected to Retard hose and connect another gauge to Advance hose. Start engine and raise speed until Advance gauge shows 5.5-6.3 in. (140-160 mm) Hg vacuum. Vacuum should not be present at Retard gauge. If vacuum does not disappear at correct level, replace vacuum switch and retest.
- If vacuum does not reach proper level on Advance gauge, check for leaks and retest. If vacuum does not disappear, hold Advance vacuum at 6.3 in. (160 mm) Hg. Check for voltage between Green and Black/Yellow wires at left side of emission control box. If no voltage, check fuses and wiring. If voltage, check at the ignition solenoid valve (Yellow wire). If voltage is present there, replace valve. If not, check and repair wiring.
- Remove delay valve. Connect a hand vacuum pump and 11 in. (280 mm) piece of 1/8 in. (3.5 mm) hose to check valve side of delay valve. Plug other two ends and check for vacuum leaks. Apply vacuum to distributor side. If a vacuum can be obtained, replace valve.
- Plug air filter bleed orifice and apply vacuum to check valve side. Vacuum should decrease from 15 in. (380 mm) Hg to 5 in. (130 mm) Hg in 4-9 seconds. If not, replace valve.NOTE: If specified hose length and diameter are not used, vacuum leak times may vary.
- Reinstall delay valve. Connect a vacuum pump to distributor Advance hose and start engine. Pull 14 in. (360 mm) Hg vacuum. Timing should advance and hold; if not, replace diaphragm. Repeat test at Retard diaphragm.