Mercury MERCRUISER, Service Manual, Page: 88 / 566

Step Action Yes No
1 Was the
Visual/Physical Check
completed? Go to step 2.
Go to the
Visual/Physical
Check
.
2
Did the onboard diagnostic (OBD) system check
complete?
Go to step 3.
Connect the CDS G3 service tool
and scan for faults.
3
Check for proper fuel pressure while the condition
exists.
Was a problem found?
Go to
Chart T3
. Go to step 4.
4
Check the fuel injectors.
Was a problem found?
Repair or replace the faulty
injector.
Go to step 5.
5
Check for obvious overheating issues:
• Loose serpentine belt
• Faulty or incorrect seawater pump
• Restriction in the cooling system
• Faulty or incorrect thermostat
Was a problem found?
Repair or replace.
Retest the system.
Go to step 6.
6
Check the fuel pump relay for proper operation.
Was a problem found?
Repair or replace.
Retest the system.
Go to step 7.
7
Review all of the procedures in this table. If all procedures have been completed and no problem found, inspect the
following:
• CDS G3 scan tool data
• All of the electrical connections within a suspect circuit or system
Chart S9: Backfire
Definition: Fuel ignites in the intake manifold or in the exhaust system, making a loud popping noise.
Step Action Yes No
1 Was the
Visual/Physical Check
completed? Go to step 2.
Go to the
Visual/
Physical Check
.
2 Did the onboard diagnostic (OBD) system check complete? Go to step 3.
Connect the CDS G3
service tool and scan
for faults.
3
Check the flame arrestor for dirt, damage, or any restriction.
Was a problem found?
Clean or replace the flame
arrestor.
Go to step 4.
4
• Check for contaminated fuel.
• Check fuel filters and the water‑separating fuel filter.
• Check for poor fuel quality and improper octane rating.
Was a problem found?
Use known good fuel.
Replace the fuel filters.
Go to step 5.
5
Check for proper fuel pressure while the condition exists.
Was a problem found?
Go to
Chart T3
. Go to step 6.
6
Check the fuel injectors.
Was a problem found?
Repair or replace the faulty
injector.
Go to step 7.
7
Check the spark plug wires for open circuits, cracks in the
insulation, or improper seating of the terminals at the spark plugs
and coil tower.
Was a problem found?
Locate and repair or replace.
Retest the system.
Go to step 8.
8
Check the ignition coil for cracks or carbon tracking.
Was a problem found?
Repair or replace the ignition
coil.
Retest the system.
Go to step 9.
9
Check for adequate spark at all of the spark plugs.
Was adequate spark present?
Go to step 10. Go to
Chart T4
.
Troubleshooting
Page 1D-18 © 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015