Fuel Pump: Description and Operation

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.