The Fuel Shut-Off System was introduced in 1981 B310 USA models. It leverages the anti-diesel valve to stop the fuel flow during periods of deceleration. This is similar to what EFI systems do. It is only active at higher speeds, namely above 40mph.
FSOS was used by CAL, FED, FED.MPG and CAN.MPG models. Canada models did not use fuel-shut off except for MPG (FU Engine) models.
For safety and good performance, the FSOS does not work unless the engine is decelerating.
- Only works when decelerating (vacuum is high AND speed above 40mph)
- Does not work in nuetral, so engine will not stop due to lack of fuel
- Does not work when clutch is engaged (so you can blip the throttle)
Components are:
- Anti-diesel valve (solenoid)
- Vacuum valve
- Speedometer speed switch, amplifier and relay
- Also used by CAL Mixture Ratio Rich-Lean Exchange System
- Automatic Transmission inhibitor switch
- Manual Transmission nuetral switch
- Clutch pedal switch
This would be an interesting system to retrofit to older models for increased fuel economy.