Suzuki DF200 - High Pressure Fuel Pump Control System

ENGINE CONTROL SYSTEM 3-25
HIGH PRESSURE 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 (1 000 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.
CONTROL MODES
BEFORE START:
For 6 seconds after the 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 50 – 100% duty based on the current engine speed and battery volt-
age.
CKP sensor:
Informs ECM of engine speed.
Ignition switch:
Informs ECM of “START” signal.
Battery voltage
ECM
Signal FP
Fuel pump
Duty cycle signal for fuel pump
(example: 80% duty)
“ON” time
1 cycle time
× 100 = duty (%)
0.8 ms
Time
1 ms (1cycle)
OFF
ON
Battery
charge
coil
Rectifier &
regulator
60A fuse
30A fuse
15A fuse
Battery
ECM
main
relay
Ignition
switch
Fuel pump
ECM
CPU
FP
Sensor/switch
signal input.