Suzuki GSX-R750, Service Manual, Page: 158 / 495

FI SYSTEM AND INTAKE AIR SYSTEM 4-11
Relief valve
Brush
Outlet port
Check valve
Armature
Magnet
Impeller
Inlet port
Outlet
Blade groove
Inlet
Flow clearance
Turning direction
Motor shaft
Vortex flow
Impeller
FUEL PUMP
The electric fuel pump is located under the fuel tank, which consists of the armature, magnet, impeller,
brush, check valve and relief valve. The ECM controls its ON/OFF operation as controlled under the FUEL
PUMP CONTROL SYSTEM.
When electrical energy is supplied to the fuel pump, the motor in the pump runs and so does the impeller. This
causes a pressure difference to occur between both sides of the impeller as there are many grooves around
it. Then the fuel is drawn through the inlet port, and with its pressure increased, it is discharged through the
outlet port. The fuel pump has a check valve to keep some pressure in the fuel feed hose even when the fuel
pump is stopped. Also, the relief valve is equipped in the fuel pump, which releases pressurized fuel to the
fuel tank when the outlet of the fuel pressure has increased up to 450 – 600 kPa (4.5 – 6.0 kgf/cm
2
, 64 – 85
psi).
When the impeller is driven by the motor, pressure differential occurs between the front part and the rear
part of the blade groove as viewed in angular direction due to fluid friction. This process continuously takes
place causing fuel pressure to be built up. The pressurized fuel is then let out from the pump chamber and
discharged through the motor section and the check valve.