H1 V8-6.5L DSL (1998)
Diesel MFI Pump: Description and Operation
Electronic Fuel Injection Pump Operation
Electronic Fuel Injection Pump Operation
The electronic fuel injection pump is operated by the powertrain control module. The pump contains a fuel solenoid driver, an optical and fuel
temperature sensor, a shut off solenoid, a stepper motor, and a fuel solenoid. Additional signal sources that affect pump operation are: crankshaft
position sensor, boost sensor, coolant temperature sensor, intake air temperature sensor, and electronic accelerator pedal.
At initial engine start, the fuel/lift pump continuously supplies fuel to the injection pump.
A change in accelerator pedal position to part throttle, causes an equivalent change in pedal potentiometer voltage output. The PCM then signals the
solenoid driver to increase fuel flow. Flow rates are further refined based on various signals from engine sensors.
The boost/baro sensor monitors changes in intake manifold pressure. Pressure changes are converted into a voltage signal transmitted to the PCM. High
voltage readings indicate high manifold pressures and low voltage indicates low pressure.
The intake air temperature sensor monitors incoming air temperature. Cold air generates high sensor resistance readings while warm air generates lower
readings. The resistance signals are transmitted to the PCM which richens or leans the fuel mixture as needed.
Barometric pressure is monitored by the baro sensor. The sensor signal is used by the PCM to adjust injection pump timing and fuel mixture for different
altitudes.
The stepper motor advances/retards injection timing on command by the PCM. Signals from the optical, air temperature, crankshaft position, coolant
temperature, and fuel temperature sensors, are all utilized by the PCM to optimize settings.
Fuel injector cycles are monitored by the PCM (which controls injection). The fuel solenoid driver returns a pulse width signal to the PCM every time it
seats the fuel solenoid. This signal indicates injection has occurred at one of the injectors, and the length of the injection cycle.
