Chart R4: Engine Cranks Over But Will Not Start - Mercury MerCruiser Service Manual

Troubleshooting
Step Diagnostic Process
Verify that at least 9.5 V are available
to the solenoid at terminal "S," during
8 cranking.
Is there adequate voltage to
engage the starter solenoid?
With the key in the start position,
check for battery voltage at terminal
9 86 of the starter relay socket.
Is the voltage within 1.0 V of
battery?
Verify that at least 9.5 V are available
to the starter motor during cranking.
10
Is there adequate voltage to turn
the starter motor?
Remove the starter assembly from
the engine. Test it with a 12‑volt
11
source.
Does the starter operate correctly?
Uncouple the engine from the
sterndrive.
12
Does the engine turn over with the
sterndrive disconnected?
13
Is the motor locked up?

Chart R4: Engine Cranks Over but Will Not Start

This procedure is intended to diagnose a PCM 112 mechanical shift engine that rotates the crankshaft, but will not start when
the key switch is held in the start position. You are here because you answered no to step 4 of the diagnostic roadmap.
Step Diagnostic Process
Did you complete the Visual/Physical
1
Check?
Use the CDS G3 service tool to check for
2 faults.
Are there any faults?
Check for adequate spark at all of the
3 spark plugs.
Was adequate spark present?
Connect a known good fuel source in
4 place of the boat's fuel tank.
Does the engine start?
Inspect the fuel filter.
5
Is the fuel filter obstructed?
Check the fuel pressure at the fuel rail.
Was the fuel pressure within
6
specification when the pump was
operating?
Page 1D-8
Details
Refer to Section 4A ‑ Low
Voltage Tests .
–
Refer to Section 4A ‑ Low
Voltage Tests .
–
–
Check for water in cylinders,
internal mechanical issues, and
corrosion.
Details
If a sensor has failed, it will
normally set a fault in the
PCM. For the CPS, see the
note, following.
Refer to Section 5A ‑ Fuel
Pressure Gauge Setup
and Use.
© 2016 Mercury Marine
Replace the starter
solenoid or the starter
motor assembly.
Test the relay (refer to
PCM 112–Section 3A ‑
Component testing).
• If the relay is bad,
replace it and retest
the system.
• If the relay is good,
there is an open
between the relay
and the solenoid.
Go to step 11.
Inspect the flywheel ring
gear for damage. If it
appears okay, reinstall
the starter. Go to step 12.
The problem is in the
sterndrive. Refer to the
appropriate sterndrive
service manual.
Refer to Section 3 ‑
Engine Mechanical.
– Go to step 2.
Troubleshoot the faults.
Refer to the PCM 112
Service Manual.
– Go to step 4.
The problem is with the boat
–
fuel supply.
Clean or replace the fuel
– filter. Test the fuel for
contaminants.
Go to step 7.
90-8M0099748 eng DECEMBER 2015
Yes No
Go to step 9.
There is a problem
in the circuit that
supplies voltage to
terminal 86 of the
starter relay.
Perform the Voltage
Drop Test in
Section 4A ‑
Starting System.
The starter assembly
is bad.
Go to step 13.
Contact Mercury
Product Service.
Yes
Perform the
Visual/Physical
Check.
Go to step 3.
Go to Chart T4.
Go to step 5.
Go to step 6.
Go to Chart T3.
No