55074T Mercruiser THRUST HUB

Recommended Actions
Download the Product Status Report from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. Troubleshoot any active codes before continuing with this procedure.
Table 1
Troubleshooting Test Steps Values Results
1. Inspection of the Fuel Supply
A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.
B. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
Fuel level
Result: The fuel level is OK.
Proceed to Test Step 2.
Result: The fuel level is not OK.
Repair: Fill the tank.
2. Engine Shutdown Switches (if applicable)
A. The engine shutdown switches must be in the OFF position.
B. Use Cat ET to verify the status of the engine shutdown switches. When a shutdown occurs, the keyswitch must be turned to the OFF position for at least 15 seconds before restarting the engine.
Switches are in the OFF position
Result: The switches are in the OFF position.
Proceed to Test Step 3.
Result: The switches are not in the OFF position.
Repair: Turn the switches to the OFF position.
3. Starting Aids (if applicable)
If cold ambient conditions exist, check the operation of the starting aids.
Verify that the starting aid is operating correctly.
Starting aids are operational
Result: The starting aid is operating correctly.
Proceed to Test Step 4.
Result: The starting aid is not operating correctly.
Repair: Refer to the appropriate circuit test in order to troubleshoot the starting aid.
4. Restrictions in the Air Inlet and Exhaust System
A. Check for an air filter restriction indicator.
B. Check the air inlet and exhaust system for restrictions and/or leaks.
Air and Exhaust System restrictions
Result: There are no system restrictions.
Proceed to Test Step 5.
Result: There are system restrictions.
Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System" for additional information on the air inlet and exhaust systems.
Repair: Replace plugged air filters. Refer to the Operation and Maintenance Manual for the correct procedure.
5. Theft Deterrent System (if applicable)
A. Verify that the theft deterrent system is not active.
Theft system is inactive.
Result: The theft deterrent system is not active.
Proceed to Test Step 6.
Result: The theft deterrent system is active.
Repair: Turn the theft deterrent system OFF.
6. Sensors
A. The coolant temperature sensor must provide a correct signal in order for cold mode operation to operate correctly.
Refer to "Cold Mode Operation" within the Systems Operation, "General Information".
B. Verify that the coolant temperature on Cat ET is reasonable for the conditions that are present.
Sensor output
Result: The sensor is operating properly.
Proceed to Test Step 7.
Result: The sensor is not operating properly.
Repair: Refer to Troubleshooting, "Sensor Signal (Analog, Passive) - Test" for troubleshooting information.
7. Engine Speed/Timing
A. Crank the engine and observe the engine speed on the Cat ET status screen. Refer to Troubleshooting, "Speed/Timing - Test" for additional information.
Upon initial cranking, the status for engine speed may indicate that the engine speed signal is abnormal. This message will be replaced with an engine speed once the ECM is able to calculate a speed from the signal.
Timing signal
Result: The timing sensor is operating properly.
Proceed to Test Step 8.
Result: The timing sensor is not operating properly.
Repair: Refer to Troubleshooting, "Speed/Timing - Test" for troubleshooting information.
8. Fuel System
A. Inspect the fuel system. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for additional information.
B. Cold weather adversely affects the characteristics of the fuel. Refer to the engines Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation.
C. Check fuel quality. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for the proper procedure. Check the fuel tank for debris or foreign objects which may block the fuel supply.
D. Check the filtered fuel pressure while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for the test procedure and for the correct pressure values.
If the fuel pressure is low, replace the fuel filters. Clean the primary filter/water separator of debris. Refer to the Operation and Maintenance Manual for details.
E. Check for the proper operation of the fuel transfer pump. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for test information.
Low-pressure fuel system
Result: The low-pressure fuel system is not operating properly.
Repair: Make the necessary repairs. Return the engine to service.
Result: The low-pressure fuel system is operating properly.
Proceed to Test Step 9.
9. HEUI Fuel Injection Pump
A. Check the operation of the HEUI fuel injection pump. Refer to Troubleshooting , Injection Actuation Pressure - Test.
HEUI fuel injection pump
Result: The HEUI fuel injection pump is within specifications.
Return the unit to service.
Result: The HEUI fuel injection pump is not within specifications.
Result: Replace the HEUI fuel injection pump. Return the unit to service.