Fuel Pump Control System - Suzuki DF 60 Service Manual

FUEL PUMP CONTROL SYSTEM

OUTLINE
To supply the optimum fuel amount, the ECM controls the fuel pump drive duty cycle, a repeated ON / OFF
signal, at a specified rate (1000 times a second).
Based on engine speed and battery voltage, the ECM determines the optimum duty (repeating "ON" time
rate within a cycle) and sends this signal to the fuel pump.
CKP sensor:
Informs ECM of engine speed.
Battery voltage:
Ignition switch:
Informs ECM of "START" signal.
Battery
charge
coil
Rectifier &
regulator
30A fuse
Ignition
switch
Battery
CONTROL MODE
BEFORE START:
For 3 seconds after ignition switch is turned "ON", the pump is controlled to operate at 100% duty in order to
initially pressurize the high pressure line.
WHEN CRANKING:
The pump is controlled to operate at 100% duty.
WHEN RUNNING (NORMAL OPERATION):
The pump is controlled to operate at 60 – 100% duty based on the current engine speed and battery voltage.
ECM
CPU
ECM
main
relay
15A
fuse
FP
Fuel
pump
ENGINE CONTROL SYSTEM
ECM
Duty cycle signal for fuel pump
(example: 70% duty)
OFF
Sensor/switch
ON
signal input
Signal
FP
Fuel pump
"ON" time
× 100 = duty (%)
1 cycle time
0.7 ms
1 ms (1 cycle)
3-19
Time