DESCRIPTION
This system aids in control of exhaust emissions and engine performance during prolonged periods of deceleration. System will cut off part of the fuel to carburetor slow circuit, thus leaning mixture and preventing afterburning and overheating which results from a rich mixture. System consists of a fuel cut solenoid, vacuum switch, computer, and connecting tubing and wiring.
OPERATION
Slow speed circuit in carburetor operates except during prolonged periods of deceleration at high engine speeds. Under these conditions, vacuum switch or computer turns off fuel cut solenoid valve and mixture is leaned out. This prevents overheating and afterburning in the catalytic converter.
SOLENOID VALVE
Remove valve from engine and apply battery voltage to terminals. Solenoid should click if operating properly. Check "O" ring for damage and replace if necessary. Reinstall valve.
VACUUM SWITCH
Disconnect wiring connector from switch. Using ohmmeter, check for continuity between terminal and body of switch with engine stopped. With engine running there should be no continuity. Replace switch if defective.
Tercel
Start engine and run at idle. Disconnect vacuum hose to the vacuum switch. A click should be heard/felt at the 2nd fuel cut solenoid. If so, system is working properly. If not, test switch and solenoid valve.
Land Cruiser
- Connect tachometer to engine. Start engine and check that engine idles properly. Pinch off hose to vacuum switch.
- Gradually increase engine speed to 2000 RPM (2300 RPM for Corolla). Engine should misfire slightly between 1800-3000 RPM as engine speed is raised. NOTE: Perform this procedure quickly to avoid overheating and damage to converter.
- Release hose and raise engine speed, checking to see that engine runs smoothly. Unplug wiring connector to solenoid valve. Engine should now idle rough. If engine responds as indicated, system is operating normally. Stop engine, and reconnect wiring.