RX7 2RTR- 1308cc 1.3L Turbo FI (1989)
Fuel Pump Ballast Resistor Relay: Description and Operation
Fuel Pump Control System
Water Thermosensor Testing
The Fuel Pump Resistor Relay, located in the right front corner of the engine compartment, is regulated by the ECU to reduce fuel pump operating
voltage under specified driving conditions. This results in two fuel pump operating speeds, providing for precise fuel system control, increased
component service life and quieter operation.
During cranking, the relay is not energized (not grounded at ECU terminal 1K) and the fuel pump runs on system voltage. Full voltage to the pump is
maintained under all driving conditions for 90 seconds after engine start. Following this initial period, the ECU energizes the relay at idle only, routing
fuel pump power through the resistor to reduce pump speed by lowering operating voltage. Under driving conditions other than idle, the relay remains
"OFF" and the fuel pump runs on full system voltage.
