Mercury MerCruiser MCM 454 Mag MPI Service Manual page 568

SERVICE MANUAL NUMBER 23
Hard Start Symptom (Continued)
Index
90-861326--1 MARCH 1999
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1. Check for a ECT sensor shifted in
value.
2. With engine completely cool, mea-
sure the resistance of the ECT sen-
sor.
3. Refer to the Engine Coolant Tem-
perature Sensor Temperature -vs-
9
Resistance value table on the facing
page of DTC 14 in the "Trouble Code
Diagnostics" section. Compare the
approximate temperature of the
ECT sensor to an accurate reading
of ambient air temperature.
Are the readings within the specified
value?
1. Check ECT sensor for being shifted
in value.
2. With the engine completely cool,
compare the ECT sensor tempera-
10
ture with an accurate reading of
ambient air temperature.
Are the temperatures
specified value of each other?
1. Using a scan tool, display ECT sen-
sor temperature and note value.
2. Check resistance of ECT sensor.
3. Go to Engine Coolant Temperature
Sensor Temperature -vs- Resis-
11
tance value table on the facing page
of DTC 14 in the Diagnostics sec-
tion.
Is resistance value of ECT sensor near
the resistance of the value noted?
Locate and repair high resistance or
poor connection in the ECT signal
12
circuit or the ECT sensor ground.
Is action complete?
Replace the ECT sensor.
13
Is action complete?
1. Check for intermittent opens or
shorts to ground in the MAP sensor
circuits.
14
2. If a problem is found, repair as nec-
essary.
Was a problem found?
FUEL INJECTION SYSTEM TROUBLESHOOTING
10 F
(-12 C)
within the 10 F
(-12 C)
-
-
-
-
Go to Step
Go to Step 13
14
Go to Step
Go to Step 13
11
Go to Step
Go to Step 12
14
Go to OBD
System
-
Check
Go to OBD
System
-
Check
Go to OBD
System
Go to Step 15
Check
Page 5D-9