Fuel Cut Control Unit: Testing and Inspection

1. Disconnect electrical connector from throttle switch.
2. Connect ohmmeter between throttle switch contact and ground.
3. Meter should indicate continuity with throttle closed and no continuity with throttle open. If not, adjust or replace switch as needed. Reconnect throttle switch connector.
4. Connect tachometer and suitable pulse relation meter following manufacturer's instructions, start engine and run until it reaches normal operating temperature.
5. Disconnect electrical connector from vacuum valve and ensure that battery voltage is available to valve, if not, check wiring between valve and fuse block and repair as needed.
6. Reconnect vacuum valve connector, run engine at approximately 2000 RPM, then release throttle.
7. Vacuum valve should be felt to operate, a sudden drop in engine speed should be noted and pulse relation should remain fixed at 60% until speed drops below 1300/1450 RPM.
8. If system fails to operate as outlined, consult chart below.

SYMPTOM POSSIBLE DEFECTIVE PART

Fuel shutoff not operating Decel system relay, Acceleration enrichment time relay, Throttle switch, Fuel shutoff valve.

Incorrect pulse ratio Decel system relay, Acceleration enrichment time relay, Throttle switch, Pulse relation valve, Lambda control unit