Chart S4: Hesitation, Sag, Or Stumble - Mercury MerCruiser Service Manual

Troubleshooting
Step
Using an engine cleaner, remove excessive carbon buildup
from the combustion chambers.
15 NOTE: Refer to the instructions on the engine cleaner.
Retest the system.
Is detonation still present?
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
16
NOTE: If there is an active fault Engine_Misfire , refer to the PCM 112 Service Manual or to MerCruiser Service Bulletin
‑ 11R2 .
2011
• All of the electrical connections within a suspect circuit or system

Chart S4: Hesitation, Sag, or Stumble

Definition: Momentary lack of response as the throttle lever is advanced. Can occur at all engine speeds, but usually more
severe when first starting out. May cause engine to stall in severe cases.
Step
1 Was the Visual/Physical Check completed?
2 Did the onboard diagnostic (OBD) system check complete?
Inspect the flame arrestor for restrictions, dirt, or damage.
3
Was a problem found?
Check for intermittent opens or shorts to ground in the MAP
4 sensor circuit.
Was a problem found?
• Using the scan tool, check for proper operation of the
TPS.
5
• Check throttle linkage for sticking, binding, or wear.
Was a problem found?
• Check for contaminated fuel.
• Check fuel filters and the water‑separating fuel filter.
6
• Check for poor fuel quality and improper octane rating.
Was a problem found?
Check for proper fuel pressure while the condition exists.
7
Was a problem found?
Check the fuel injectors.
8
Was a problem found?
Remove the spark plugs and check them for moisture, cracks,
wear, improper gap, burned electrodes, or heavy deposits.
NOTE: If the spark plugs are fouled with gas or oil, determine
9
the cause of the fouling before replacing the spark plugs.
Was a problem found?
Check the alternator voltage output.
10
Is the output 13.9–14.7 V?
Check for obvious overheating issues:
• Loose serpentine belt
• Faulty or incorrect seawater pump
11
• Restriction in the cooling system
• Faulty or incorrect thermostat
Was a problem found?
Page 1D-14
Action
Action
© 2016 Mercury Marine
Yes
Go to step 16.
Yes
Go to step 2.
Go to step 3.
Clean or replace the flame
arrestor.
Retest system.
Locate and repair the problem
in the harness.
Retest system.
Locate and repair the problem
with the TPS or the throttle
linkage.
Retest system.
Use known good fuel.
Replace fuel filters.
Go to Chart T3.
Repair or replace the faulty
injector.
Replace the spark plugs.
Go to step 11.
Repair or replace.
Retest system.
90-8M0099748 eng DECEMBER 2015
No
Done.
No
Go to the Visual/
Physical Check.
Connect the CDS G3
service tool and scan for
faults.
Go to step 4.
Go to step 5.
Go to step 6.
Go to step 7.
Go to step 8.
Go to step 9.
Go to step 10.
Refer to Section 4C ‑
Charging System.
Go to step 12.