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Mercury MerCruiser MCM 7.4L MPI User Manual

Mercury MerCruiser MCM 7.4L MPI
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MULTI-PORT FUEL INJECTION DISASSEMBLY AND REASSEMBLY SERVICE MANUAL NUMBER 23
Page 5C-52 90-861326--1 MARCH 1999
Knock Sensor
NOTICE
Refer to “Precautions” in this section, BEFORE proceeding.
NOTE: The 7.4L MPI has a knock sensor mounted on the port and starboard sides of the
engine block.
REMOVAL
1. Disconnect electrical connector at knock sensors located just ahead of starter motor.
75678
a
Starboard Side Shown
a-Knock Sensor
2. Remove both knock sensors from engine block.
CLEANING AND INSPECTION
1. Clean knock sensors with a dry cloth, paying special attention to threads on base.
2. Inspect surfaces of knock sensors for signs of wear or physical damage.
INSTALLATION
IMPORTANT: If installing a new knock sensor, be sure to replace it with an identical
part. Knock sensors are very sensitive and designed for each specific application.
IMPORTANT: In the following step, it is very important that the knock sensor be
torqued to the precise specification. Incorrect torquing will result in unsatisfactory
performance. DO NOT
use sealer on threads.
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Mercury MerCruiser MCM 7.4L MPI Specifications

General IconGeneral
Engine TypeV8
Bore4.25 in (108 mm)
Compression Ratio8.6:1
Ignition SystemElectronic Ignition
Alternator65 Amp
Displacement7.4L (454 cu in)
Fuel SystemMulti-Port Fuel Injection (MPI)
Horsepower310 HP
Torque450 lb-ft
Cooling SystemClosed Cooling
Fuel Requirement87 octane (minimum)
Stroke4.00 in (101.6 mm)

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