ENGINE
L3301, L3901, L4701, WSM
1-M8
Feed Pump
The feed pump (1) is installed after the fuel cooler
and has a function of suctioning fuel from the fuel tank
and feeding it through a filter and to the supply pump.
Operating
During the up stroke, the piston (4) is pushed up by
the fuel cam (7) via the tappet (6) and push rod (12). As
a result, the pressure in the inner chamber (8) rises, the
suction side check valve (2) closes and the discharge
side check valve (9) opens. On the other hand, the
pressure in the outer chamber (11) is lowered so the
suction side check valve (5) opens and discharge side
check valve (10) closes.
During the down stroke, the piston is lowered by a
piston spring (3) and the pressure in the inner chamber
is lowered so the suction side check valve (2) opens and
discharge side check valve (9) closes. On the other
hand, the pressure in the outer chamber rises so the
suction side check valve (5) closes and discharge side
check valve (10) opens.
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[2] SUPPLY PUMP
The supply pump corresponds to conventional
injection pumps but pressurizes the fuel to more than 2
times that of conventional pumps for delivery to the rail.
The supply pump is made up of an intake adjustment
valve (SCV) (3), pressurizing part, overflow valve (4), IO
valve (6), and zero delivery drain (5).
• Rail pressure changes based on engine
conditions.
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(1) Feed Pump
(2) Suction Side Check Valve
(3) Piston Spring
(4) Piston
(5) Suction Side Check Valve
(6) Tappet
(7) Fuel Cam
(8) Inner Chamber
(9) Discharge Side Check Valve
(10) Discharge Side Check Valve
(11) Outer Chamber
(12) Push Rod
(A) Suction Side
(B) Discharge Side
[A] Up Stroke
[B] Down Stroke
Supply Pump Type
Rail pressure reference values
MPa (kgf/cm
2
)
At Idling At Rated Speed
PF49
25 to 30 MPa
260 to 300 kgf/cm
2
3700 to 4300 psi
65 to 70 MPa
663 to 713 kgf/cm
2
9500 to 10000 psi
(1) Eye Bolt (out)
(2) Eye Bolt (in)
(3) Suction Control Valve (SCV)
(4) Overflow Valve
(5) Zero Delivery Drain
(6) IO Valve
(A) To fuel tank
(B) To rail
(C) From fuel filter
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