Mariner Mercury 105/140 JET, Руководство по обслуживанию

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3C-18 - FUEL SYSTEMS 90-824052R3 JUNE 2002
DETONATION CONTROL SYSTEM FUNCTION
1. Combustion noise (or vibration) excites the
piezoelectric circuit located inside the detonation
sensor, which transmits a voltage to the control
module.
2. When cylinder number two ignition primary fires,
it signals the controller to look at a one
millisecond window of sensor output, which it
retains as a reference level of combustion
“background noise.”
3. When “background noise” reaches a measurable
value, usually between 2500 and 3500 RPM (it is
dependent on load), the ignition timing is
advanced 6 degrees beyond what the
mechanical timing is set at. Timing advance is
accomplished by lowering the bias voltage.
4. The controller continues to monitor sensor out-
put. If the output exceeds a pre-determined
threshold level over the “background noise”
(which is indicative knock is occurring) ignition
timing is retarded by up to 8 degrees and fuel flow
is enriched by up to 15% until the sensor output
is reduced below the threshold level.
The detonation control system actually acts as an
ignition advance module, when knock occurs it takes
away the advance. Ignition timing will not advance if:
a. Knock sensor fails.
b. Blue/White wire becomes disconnected.
c. Black wire has poor ground connection.
d. Purple power wire becomes disconnected.
NOTE: Disconnected Gray/White wire will not affect
ignition timing and will not allow fuel enrichment.
Other components associated with the ECM.
12 Volt Battery -The 12 volt battery provides power
to the ECM even with the ignition switch in the “OFF”
position.
IMPORTANT: When disassembling EFI System
DISCONNECT BATTERY CABLES.
Starter Solenoid - Provides 12 volt signal when key
is in the “start” position. In the “start” position, injector
pulse widths are tripled when engine head
temperature is below 90
°
F (32.2
°
C) to provide
adequate fuel for quick start up. When key is returned
to the run position or engine head temperature is
above 90
°
F (32.2
°
C), pulse widths return to normal
value.
Fuel Injectors - A four wire harness connects the
fuel injectors to the ECM. The red wire is at 12 volts
and connects to all injectors. The blue, yellow and
white wires each go to a pair of injectors and are
normally at 12 volts for a zero differential. To fire the
injectors this voltage is brought down to near ground
creating a potential across the injectors.
Electric Fuel Pump - The ECM contains a fuel pump
driver circuit that provides power to the electric fuel
pump (2 speeds). The fuel pump does not have its
negative terminal (-) “RED/PURPLE wire” grounded
to the pump housing. The fuel pump positive terminal
(+) “RED wire” and the negative terminal (-) are at 12
volts with the ignition switch in the off position for a
zero differential. When the pump is on, the negative
terminal is brought down to near ground (i.e. 1.5 volts
at high speed).
WATER SENSING SYSTEM
The system consists of a water separating fuel filter
(starboard side powerhead), sensing probe (bottom
of filter) and a water sensing module (below ECM
box). The water sensing module has four wires:
PURPLE - Connects to 12 volt power supply.
LIGHT BLUE - Connects to lube alert, which sounds
the warning horn when activated.
TAN - Connects to sensing probe.
BLACK - Connects to ground.
WATER SENSING SYSTEM FUNCTION
1. The filter separates the accumulated water from
the fuel.
2. A voltage is always present at sensing probe.
When water reaches top of probe it completes
the circuit to ground.
3. The completed circuit activates the warning. The
warning has a 5-10 second delay, then the
module’s red light illuminates and warning horn
intermittently sounds.
The system can be tested by disconnecting the TAN
wire from sensor probe and holding to a good engine
ground connection for 10 seconds.