The major components of the throttle body assembly
include the TP sensor and the throttle body housing
assembly.
High Pressure Fuel Rail
E219399
1
2
3
4
FRP sensor
1
High pressure fuel rail
2
High pressure fuel rail removed
3
Fuel injector
4
The high pressure fuel pump supplies fuel to the fuel
rail which distributes fuel to the fuel injectors. When
the fuel injectors are opened by a signal from the PCM
the fuel is injected into the cylinder.
The FRP sensor is a diaphragm strain gauge device
which measures the pressure difference between the
fuel rail and atmospheric pressure.
The FRP sensor nominal output varies between 0.5 and
4.5 volts, with 0.5 volts. The sensor can read vacuum
and may lower the output voltage to slightly below 0.5
volts.
This condition is normal and is usually the case after
several hours of cold soak before the vehicle dome light
is turned ON.
The FRP sensor is located on the fuel rail and provides
a feedback signal to indicate the fuel rail pressure to the
PCM. The PCM uses the FRP signal to command the
correct injector timing and pulse width for correct fuel
delivery at all speed and load conditions. The FRP
sensor, along with the fuel volume regulator (part of the
fuel injection pump), form a closed loop fuel pressure
control system.
High Pressure Fuel Pump
E217867
x2
The high pressure fuel pump is located at the rear of the
engine and is driven by a four sided cam on the exhaust
camshaft. The high pressure fuel pump increases fuel
rail pressure to the desired level to support fuel injection
requirements.
37
Service Training
Fuel Charging and Controls
Lesson 3 – Powertrain
