2. Fuel Pressure Regulator
– Pressurized fuel from the pump is sent through this devise where it is
regulated at a certain, constant pressure (H-D spec is 55-62 PSI) to the fuel injectors. Consistent fuel
pressure is required for a properly running engine. Excess, non-regulated fuel is returned to the gas
tank. Located in the gas tank on 2001-up Softails®, 2002-up all models (on 1995-2001 Touring
models, the regulator is mounted externally, on the throttle body). The second fuel line on 1995-2001
Touring models is the return line for excess fuel since the regulator is mounted externally.
3. Fuel Rail
– Essentially the manifold for fuel delivery to the fuel injectors. Mounted to the intake
manifold of the throttle body, the pressurized fuel line and one side of the fuel injectors are attached
to it.
4. Fuel Injectors
– Electronic on/off valves for injecting pressurized fuel in short pulses into the
engine. Pressurized fuel enters the injector from the fuel rail where a small electronic solenoid opens
and closes for a specified time to deliver fuel to the engine, where it is mixed with air being drawn into
the intake port. The exact timing and duration of the fuel pulse (pulse width) is controlled by the
motorcycle’s Electronic Control Module (ECM).
5. Throttle Body
– Air and fuel are fed into the engine through the throttle body and manifold
assemblies. Sensors are mounted to the throttle body to provide feedback to the ECM regarding
throttle position, manifold pressure and intake air temperature. A small electric motor is attached to
control engine idle speed.
6. Throttle Position Sensor (TPS)
– Electronic sensor mounted to the end of the throttle shaft that
transmits throttle blade position (twist-grip position) to the ECM.
7. Manifold Air Temperature (MAT) Sensor
– Relays information to the ECM so it can adjust engine
requirements based on intake air temperature. Mounted on the throttle body, behind the throttle
blade.
8.
Manifold Absolute Pressure (MAP) Sensor
- Relays information to the ECM so it can adjust
engine requirements based on intake manifold pressure. Mounted on the throttle body, behind the
throttle blade.
9. Cylinder Head Temperature Sensor – Monitors engine temperature and relays information to the
ECM. Used by ECM to alter settings for warm-up, normal operating and over-temperature situations.
10.
Idle Air Control (IAC)
Motor – Small electric motor with a pointed-tip plunger that controls the
amount of air the engine receives during idle. Mounted to the throttle body, midway on the Idle
