86908 Mercruiser TUBE, WATER - GIMBAL HOUSING

Probable Causes
Diagnostic codes
Engine accessories and transmission
ECM parameters
Throttle signal from the throttle position sensor
Air intake and exhaust system
Fuel system inspection
Fuel filters
Low compression (cylinder pressure)
Individual malfunctioning cylindersRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. Establish communication between the electronic service tool and the Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary.
Diagnostic codes
Result: There are active or logged codes.
Repair: Troubleshoot any codes before continuing with this procedure.
Result: There are no active or logged codes.
Proceed to Test Step 2.
2. Engine Accessories and Transmission
A. Check that the engine accessories and transmission are operating correctly.
B. Remove and inspect any engine accessories that may be adding unexpected load to the engine.
Engine accessories and transmission
Result: The engine accessories and transmission are not OK.
Repair: Make the necessary repairs.
Result: The engine accessories and transmission are OK.
Proceed to Test Step 3.
3. ECM Parameters
A. Use the electronic service tool to verify that the correct engine parameters are being used. Refer to Troubleshooting, "Configuration Parameters" for additional information.
Parameters
Result: The parameters are not configured correctly.
Repair: Correctly configure the parameters.
Verify that the configuration change eliminated the fault.
Result: The parameters are configured correctly.
Proceed to Test Step 4.
4. Throttle Signal From the Throttle Position Sensor (if equipped)
A. If a fault is suspected in the throttle sensor, refer to Troubleshooting, "Speed Control - Test".
Throttle position sensor faults
Result: The throttle position sensor or the associated wiring is faulty.
Repair: Repair or replace the throttle position sensor or the associated wiring.
Result: The throttle position sensor and the associated wiring are OK.
Proceed to Test Step 5.
5. Air Intake and Exhaust System
A. Check the air filter restriction indicator, if equipped. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual.
B. Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Systems Operation, Testing and Adjusting, "Air Inlet and Exhaust System - Inspect".
Restrictions
Result: The air filter is plugged.
Repair: Clean or replace the air filter. Refer to the Operation and Maintenance Manual for further information.
Result: There are restrictions in the air inlet or exhaust system.
Repair: Make the necessary repairs, Verify that the repair eliminated the fault.
Result: There are no restrictions in the air inlet or exhaust system.
Proceed to Test Step 6.
6. Fuel System Inspection
A. Check that the fuel shut-off valve is in the OPEN position.
B. If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).
C. Check for fuel supply lines that are restricted.
D. Check that the low-pressure fuel lines are correctly installed.
E. Check the pressures in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Fuel System Pressure - Test"
F. Check the diesel fuel for contamination. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test".
G. Check for air in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Air in Fuel - Test".
H. Ensure that the fuel system has been primed. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".
Fuel System
Result: A defect was found in the fuel system.
Repair: Make any necessary repairs.
Result: No defects found.
Proceed to Test Step 7.
7. Fuel Filters
A. Replace the primary fuel filter and the secondary fuel filter. Refer to the Operation and Maintenance Manual, "Fuel System Primary Filter (Water Separator) Element - Replace".
B. Run the engine at top speed.
Top speed
Result: The engine reaches top speed.
Return the engine to service.
Result: The engine does not reach top speed.
Proceed to Test Step 8.
8. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test ".
Low compression
Result: Low compression is recorded on one or more cylinders.
Repair: Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Make any repairs, as necessary.
Result: No faults found.
Proceed to Test Step 9.
9. Individual Malfunctioning Cylinders
A. With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test". As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be a noticeable change in the sound of the engine.
Cylinders
Result: There is not a noticeable change in the sound of the engine for at least one cylinder.
Repair: Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.
Result: There is a noticeable change in the sound of the engine for each cylinder.
Contact the Dealer Solution Network (DSN).