Fuel Supply System

Fuel Supply System

Fuel Cutoff Control
During deceleration with the throttle valve closed, current to the injectors is cutoff to improve fuel economy at engine speeds over 850 rpm (M/T: 950 rpm). Fuel cutoff control also occurs when the engine speed exceeds 6,900 rpm, regardless of the position of the throttle valve, to protect the engine from over-revving. When the vehicle is stopped, the ECM/PCM cuts the fuel at engine speeds over 5,000 rpm (M/T: 5,550 rpm). On a cold engine, fuel cut occurs at a lower engine speed.

Fuel Pump Control (J32A3 engine)
When the ignition is turned on, the ECM/PCM grounds PGM-FI main relay 2 which feeds current to the fuel pump for 2 seconds to pressurize the fuel system. With the engine running, the ECM/PCM grounds PGM-FI main relay 2 and feeds current to the fuel pump. When the engine is not running and the ignition is on, the ECM/PCM cuts ground to PGM-FI main relay 2 which cuts current to the fuel pump.

Fuel Pump Control (J35A8 engine)
When the ignition switch is turned on, the ECM/PCM grounds PGM-FI main relay 2 which feeds current to the fuel pump control module. The ECM/PCM sends a signal to the fuel pump control module to operate the fuel pump for 2 seconds to pressurize the fuel system. With the engine running, the fuel pump speed is controlled in four levels by the fuel pump control module. The ECM/PCM decides the fuel pump speed by the calculation of the injector activation time and engine speed and sends an operation command signal to the fuel pump control module. This operation makes it possible to decrease fuel pump noise at low engine speed.

PGM-FI Main Relay 1 and 2
PGM-FI main relay 1 is energized whenever the ignition switch is ON (II) to supply battery voltage to the ECM/PCM, power to the injectors, and power for PGM-FI main relay 2. PGM-FI main relay 2 is energized to supply power to the fuel pump for 2 seconds when the ignition switch is turned ON (II), and when the engine is cranking or running.