Fuel Interruption Control
When the vehicle is decelerating with the throttle valve closed, the electrical current to the injectors is interrupted to improve fuel economy at engine speeds above 900 rpm (min⁻¹) under no electrical load (under high electrical load condition: 1,500 rpm (min⁻¹). Fuel cut-off also occurs to protect the engine from overspeed if the engine speed exceeds 6,200 rpm (min⁻¹), regardless of the throttle position. When the vehicle is stationary, the ECM cuts off fuel at engine speeds above 6,200 rpm (min⁻¹). The fuel cut-off rate is slower when the engine is cold.
Fuel pump control
When the ignition switch is turned on, the ECM grounds the PGM-FI main relay 2 (FUEL PUMP), which supplies current to the fuel pump for 2 seconds to increase fuel system pressure. When the engine is running, the ECM grounds the PGM-FI main relay 2 (FUEL PUMP), and supplies current to the fuel pump. When the ignition switch is turned on but the engine is not running, the ECM interrupts the ground to the PGM-FI main relay 2 (FUEL PUMP), which interrupts the electrical supply to the fuel pump.
Main relays 1 and 2 of the PGM-FI module
The PGM-FI module main relay 1 is energized whenever the ignition switch is turned to the ON (II) position to supply battery voltage to the ECM, supply power to the injectors, and supply power to the PGM-FI module main relay 2 (FUEL PUMP). The PGM-FI module main relay 2 (FUEL PUMP) is energized to supply electrical power to the fuel pump for 2 seconds when the ignition switch is turned to the ON (II) position and when the engine is cranking or running.
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