Full Load Fueling Circuit

To obtain maximum engine power, it is necessary to inhibit the closed loop control system and enrichen the fuel mixture. This is accomplished by using a vacuum operated electrical switch, sensing intake manifold vacuum, and a micro switch, operated by the throttle pulley spindle. The 2 switches are wired in parallel so that either or both can signal the need for full load fueling.

The micro switch is mounted so that it is closed when the throttle is opened beyond a certain point. As the throttle is opened beyond this point, the switch signals the ECU that full load fueling is necessary. The micro switch is necessary when the vehicle is traveling at high speeds under full load conditions when intake manifold vacuum is insufficient to close the vacuum operated full load switch.

The contacts of the vacuum operated switch are actuated by a spring loaded diaphragm that senses intake manifold vacuum. When the manifold vacuum falls to low levels due to part throttle full load operation, the diaphragm closes the switch contacts. This causes the fuel system to go into an open loop mode and enriches the fuel/air mixture about 12%.