Suzuki DF 50 Service Manual

ENGINE CONTROL SYSTEM 3-18
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.
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 80 – 90% duty based on the current engine speed and battery voltage.
CKP sensor :
Informs ECM of engine speed.
Battery voltage :
Ignition switch :
Informs ECM of “START” signal.
ECM
Fuel pump
Signal
FP
ECM
CPU
Sensor / switch
signal input
FP
Fuel pump
15A
fuse
Ignition
switch
Battery
30A fuse
Rectifier &
regulator
Battery
charge
coil
ECM
main
relay
Duty cycle signal for fuel pump
(example : 80% duty)
“ON” time
1 cycle time
× 100 = duty (%)
OFF
ON
0.8 ms
Time
1 ms (1cycle)

Suzuki DF 50 Specifications

General

Engine Type	4-Stroke
Cylinders	3
Displacement	941 cc
Starting System	Electric
Steering	Remote
Engine Type Detail	DOHC 12-Valve
Maximum Output	50 HP
Ignition System	Digital CDI
Alternator	12V 19A
Gear Ratio	2.27:1
Exhaust	Through Prop Hub Exhaust
Trim Method	Power Trim and Tilt
Max Power	50 HP
Alternator Output	12V 19A
Fuel Delivery System	Sequential Multi Point Electronic Fuel Injection
Full Throttle Operating Range	5, 300 - 6, 300 rpm
Engine Oil Capacity	2.7 L
Full Throttle RPM Range	5300 - 6300 RPM
Oil Capacity	2.7 L
Bore x Stroke	72.5 x 76.0 mm (2.85 x 2.99 in.)