ENGINE
L3301, L3901, L4701, WSM
1-M11
[3] RAIL
The rail (2) stores fuel at the high pressure applied
by the supply pump and the injectors of each cylinder.
The rail incorporates control parts-a rail pressure sensor
(3) and a pressure limiter (1).
The pressure of the fuel in the rail is detected by the
rail pressure sensor, and optimal feedback control is
provided for the engine RPM and load. This greatly
improves the ability to raise the pressure at low RPMs
and enables high-pressure injection from low speed
ranges.
Pressure Limiter
The pressure limiter operates when the pressure
inside the rail becomes excessively high (valve opens),
and then once the pressure drops to a certain pressure,
it acts to keep the pressure (valve closes).
Fuel discharged by the pressure limiter returns to the
fuel tank.
9Y1211012ENM0016US0
Rail Pressure Sensor
The rail pressure sensor is mounted on the rail,
detects the fuel pressure inside the rail and converts this
to an electronic signal and sends it to the ECU.
The rail pressure sensor is made up of a metal
diaphragm (1), distortion detection part (metal gauge)
(2), signal processing circuit (3), and housing etc.
When the fuel pressure (A) in the rail is applied to the
metal diaphragm, the diaphragm is distorted. Metal
gauges are set in the center and at the edge of the metal
diaphragm and tensile (C) or compression (B) force is
applied. A difference in resistance values is generated
based on the force that is applied.
Please note that the rail pressure sensor is not
available separately as a part, so replacement requires
replacing the rail assembly.
9Y1211012ENM0017US0
Valve opening pressure
Reference
value
Approx.
170 MPa
(1735 kgf/cm
2
, 24700 psi)
Valve closing pressure
Approx.
40 MPa
(408 kgf/cm
2
, 5800 psi)
(1) Pressure Limiter
(2) Rail
(3) Rail Pressure Sensor
(A) To Fuel Tank
(B) To Injector
(C) From Supply Pump
(1) Metal Diaphragm
(2) Distortion Sensor Part (Metal
Gauge)
(3) Signal Processing Circuit
(4) Voltage
(5) Pressure
(A) Fuel pressure
(B) Pressurization
(C) Tensile
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