Mercury MerCruiser MCM 454 Mag MPI Service Manual page 495

MULTI-PORT FUEL INJECTION DESCRIPTIONS AND SYSTEM OPERATION
FUEL INJECTORS
The EFI injector assembly is a solenoid-operated device, controlled by the ECM, that meters
pressurized fuel to a single engine cylinder. The ECM grounds the injector solenoid, which
opens a pintle valve, allowing fuel to flow past the pintle valve. The injector tip has holes that
control the fuel flow, generating a conical spray pattern of finely atomized fuel at the injector
tip. Fuel is directed at the intake valve, causing it to become further atomized and vaporized
before entering the combustion chamber.
An injector that is stuck partly open will cause loss of pressure after engine shutdown. This
can result in long cranking times. Dieseling or delayed shutoff can also occur, because some
fuel might be delivered to the engine after the ignition is turned OFF.
MEFI 1 Injector Shown
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Index
Page 5B-36
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q
p
a - Needle Valve
b - Nozzle
c - Cap
d - O-Ring
e - Valve Stopper
f - Core
g - O-Ring
h - Spring
i - Housing
j - Solenoid Coil
k - Tape
l - Bobbin
O-Ring
n - Inner Collar
o - Sleeve
p - Terminal
q - Connector
r - Filter
s - O-Ring
s
r
o
l
k
j
i
g
h
f
d
e
b
c
a
SERVICE MANUAL NUMBER 23
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90-861326--1 MARCH 1999
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