MARINE CORPS TM 6115-34/8
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PURPOSE AND FUNCTION OF ENGINE
AND GENERATOR CONTROLS AND INSTRU-
b. Functional Theory of Operation.
valve signal line to the engine.
valve signal being in this state opens
the engine fuel valve and allows fuel
to flow to the engine in preparation
the EECM micro-
processor software places a series of
output to an analog signal is necessary
for compatibility with inputs required
by a pulse width modulator. The level
of the resulting analog signal from the
varying square wave on the fuel pump
drive line to the engine. For startup,
the duty cycle is set at a fixed level
to drive the fuel pump at the rate
necessary to supply fuel to the engine
so that it can be started.
(c) Status monitoring/automatic
speed signal line to count pulses from
the monopole speed sensor. At the same
it monitors the EGT line.
rate of the pulses on the speed signal
line should indicate that the engine
has reached 10 percent of full oper-
because it is assumed that the engine
is not running properly or has not
action is taken by the
allowed to accelerate.
If, however, an
abnormal speed or temperature condition
first disables the ignition and starter
outputs from the microprocessor which
in turn disable the starter signal and
igniter drive signals to the engine.
signal to the switch circuit card on
one of the status/control lines.
buffering, this signal on the valve
enable line is applied to a driver that
disables the fuel valve signal line to
This shuts off fuel flow
to the engine to keep it from starting.
(d) Completion of
When 60 percent speed
the ignition enable and
starter enable lines to the switch
circuit card are disabled, shutting off
starter levels to the
The engine is considered to be
successfully started and is now allowed
to accelerate by itself.
EECM controls fuel flow to the engine
at all times after startup to ensure
that the proper amount of fuel is
It makes adjustments to the
necessary to provide
optimum fuel delivery regardless of
fuel temperature, viscosity, or load.
To determine proper flow, the micro-
processor monitors the speed signal
line and counts the rate at which
This rate is compared to
stored in the microprocessor
that represent ideal speeds for the
at various times during its
If the measured pulse
rate over time does not compare to the
the drive output from the
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