Chart R6: Engine Stalls - Mercury MerCruiser Service Manual

Troubleshooting
Step Diagnostic Process
Using the scan tool, display the ECT
sensor temperature and record the
value.
Check the resistance of the ECT
sensor.
9
Compare the approximate temperature
of the ECT sensor to an accurate
reading of ambient air temperature.
Is the ECT sensor temperature near
the resistance temperature?
Check for intermittent opens or shorts
10 to ground in the MAP sensor circuit.
Was a problem found?
Using the scan tool, check for proper
11
operation of the TPS. Was a problem
found?
Check for engine mechanical
12 problems.
Was a problem found?
Review all of the procedures in this table. If all procedures have been completed and no problem found, inspect the
following:
13
• CDS G3 scan tool data
• All of the electrical connections within a suspect circuit or system
NOTE: The crankshaft position sensor (CPS) is an exception. It will not set a fault if it fails completely.

Chart R6: Engine Stalls

This procedure is intended to diagnose a PCM 112 mechanical shift engine that starts without difficulty, but stalls while
attempting to idle or runs so poorly as to be unusable. You are here because you answered yes to step 6 of the diagnostic
roadmap.
Step Diagnostic Process
Connect a known good fuel source in
1 place of the boat's fuel tank.
Does the engine still stall?
Inspect the fuel filter.
2
Is the fuel filter obstructed?
Check the fuel pressure.
3
Is the fuel pressure steady?
Check the ground wires for loose
4 connections or corrosion.
Were problems found?
Check for mechanical engine problems.
5
Were problems found?
Page 1D-10
Details
Refer to PCM 112–Section 3A
‑Component testing..
Wiggle the MAP sensor
harness while monitoring data
on the CDS G3.
–
Check for the following:
• Low compression
• Leaking cylinder head
gaskets
• Worn camshaft
• Improper valve timing or
valve train problem
• Restricted exhaust system
Details
–
–
–
–
Check for the following:
• Low compression
• Worn camshaft
• Restricted intake or
exhaust system
© 2016 Mercury Marine
Yes
Go to step 10.
Retest the system.
Locate and repair the
open in the harness.
Locate and repair the
problem with the TPS.
Retest the system.
Refer to Section 3 ‑
Engine Mechanical.
Yes
Go to step 2.
Clean or replace the fuel filter.
Test the fuel for contaminants.
Go to step 4.
Correct the problems and
retest the engine.
Correct the problems and
retest the engine.
90-8M0099748 eng DECEMBER 2015
No
Locate and repair
high‑resistance or poor
connection in the ECT
signal circuit or the ECT
sensor ground.
Go to step 11.
Go to step 12.
Go to step 13.
No
The problem is with
the boat fuel supply.
Go to step 3.
Go to Chart T3.
Go to step 5.
Contact Mercury
Product Support.