Mercury MerCruiser MCM 454 Mag MPI Service Manual page 661

GENERAL SYSTEM DIAGNOSTICS
Chart A-3 (3 of 5): Engine Cranks But Will Not Run
Step
6
7
8
9
10
11
Index
Page 5E-68
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Action
1. Disconnect one injector electri-
cal connector.
2. Connect test light J34730-2C
to injector harness connector.
3. While cranking engine, check
for blinking light.
4. Remove test light and recon-
nect injector harness connec-
tor. Repeat this test for all injec-
tors.
5. If any lights are blinking dimly,
check for shorted injector by
comparing injector resistance
values.
Were All Lights
Brightly?
1. Install fuel pressure gauge.
2. Ignition "OFF" for 10 seconds.
3. Ignition "ON." Fuel pump will
run for about 2 seconds
4. Note fuel pressure with pump
running. The pressure may
drop after the pump stops run-
ning
Is Fuel Pressure
Specified Value?
Check for secondary
spark.
Is Adequate Spark Present At All
Cylinders?
1. Ignition "OFF."
2. Disconnect ECM "J2" connec-
tor.
3. Using a DVOM connected to
ground, probe "J2-8" of the
ECM harness connector while
cranking the englne.
Is The Voltage Within The
Specified Value?
Was The Test Light A Steady
Light?
Check the injector driver circuit
with the steady light for a short to
ground. If circuit is not shorted,
check resistance across each in-
jector in the circuit.
Is Resistance Greater Than The
Specified Value?
Value(s)
–
Blinking
Go to Step 7
34-38 psi
(234-262
kPa)
Refer to Diag-
Within
nostic Aids on
Facing Page
ignition
_
Go to Step 9
1-2 volts
Go to Step 20
Go to Step 11
_
10 Ohms
Go to Step 20
SERVICE MANUAL NUMBER 23
Yes No
Go to Step 10
Go to Chart A-4
Refer to Ignition
System Check _
Go to Step 15
Go to Step 12
Go to Step 16
90-861326--1 MARCH 1999