98548 Mercruiser WASHER, (1.125 ) (SQUARE SWIVEL SHAFT)

Probable Causes
Diagnostic codes
Fuel supply
Return fuel lines
Throttle position sensor
CAN data link
NRS valve
High-pressure fuel pump
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylinderRecommended 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.
B. Download the Histograms before performing any troubleshooting or clearing any diagnostic codes.
Note: The downloaded information will be required by the Dealer Solutions Network (DSN) if troubleshooting assistance is needed.
C. Use the electronic service tool to check for active or logged codes.
Codes
Result: There are active codes.
Repair: Troubleshoot any active codes before continuing with this procedure.
Result: There are no active codes.
Proceed to Test Step 2.
2. Fuel Supply
A. Visually check the fuel tank for fuel. The fuel gauge may be faulty.
B. Ensure that the vent in the fuel cap is not filled with debris.
C. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
D. Check the primary filter/water separator for water in the fuel.
E. Check for fuel supply or return lines that are restricted. Aged or perished fuel lines may collapse when in service and cause temporary restrictions.
F. Check that the Electric Priming Pump (EPP) is operating. If the EFLP is suspect, refer to Troubleshooting, "Fuel Transfer Pump - Test".
G. Check for air in the fuel system. Refer to Systems Operation, Testing and Adjusting, "Air in Fuel - Test".
H. Obtain a fuel analysis to confirm that the correct fuel is being used. Refer to Systems Operation, Testing and Adjusting, "Fuel Quality - Test" for the correct procedure.
Fuel supply
Result: There is air in the fuel system.
Repair: Prime the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".
Result: The fuel quality is not OK.
Repair: Replace the fuel. Replace the in line fuel filter that is upstream of the EPP. Replace the primary and secondary fuel filters. Verify that the repair eliminated the fault.
Result: The fuel quality is OK.
Proceed to Test Step 3.
3. Throttle Position Sensor
Note: This Test Step is only applicable if the machine has a hand or foot throttle.
A. Use the electronic service tool and observe the signal for the throttle position sensor. Make sure that the throttle response is smooth and progressive.
Throttle
Result: The throttle position sensor response is erratic.
Repair: Test the throttle position sensor. Refer to Troubleshooting, "Speed Control (Analog) - Test" or Troubleshooting, "Speed Control (PWM) - Test".
Result: The throttle position sensor response is OK.
Proceed to Test Step 4.
4. Check the CAN Data Link
Note: This Test Step is only applicable if the desired engine speed signal is sent through the CAN data link.
A. Use the electronic service tool to check for diagnostic codes that are related to the CAN data link.
Throttle
Result: The CAN data link is suspect.
Repair: Test the CAN data link. Refer to Troubleshooting, "CAN Data Link - Test".
Result: The CAN data link is OK.
Proceed to Test Step 5.
5. NRS Valve
A. Use the electronic service tool to perform the "Air System Motor Valve Verification Test".
Pass
Result: The "Air System Motor Valve Verification Test" failed.
Repair: Troubleshoot active diagnostic codes generated as a result of the test.
Result: The "Air System Motor Valve Verification Test" passed.
Proceed to Test Step 6.
6. High-Pressure Fuel Pump SCV
A. Use the electronic service tool to perform a solenoid test on the fuel injection pump. Refer to Troubleshooting, "Solenoid Valve - Test".
HP fuel pump
Result: The solenoid valve test fails.
Repair: Replace the HP fuel pump SCV and solenoid assembly.
Result: The solenoid valve test passes successfully.
Proceed to Test Step 7.
7. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing and Adjusting, "Compression - Test".
Cylinder compression
Result: The results of the compression test are outside the specifications.
Repair: Investigate the cause and rectify any faults.
Note: 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
Result: The results of the compression test are OK.
Proceed to Test Step 8.
Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.
Contact with high-pressure fuel may cause personal injury or death. Wait 10 minutes after the engine has stopped to allow fuel pressure to purge before any service or repair is performed on the engine fuel lines.
Table 2
Troubleshooting Test Steps Values Results
8. Electronic Unit Injectors
A. Use the electronic service tool to perform the automatic "Cylinder Cutout Test".
Note: If the compression test that was performed in Test Step 7 was satisfactory, the "Cylinder Cutout Test" will identify any faulty injectors.
Electronic Unit Injectors
Result: A faulty injector is indicated.
Repair: Remove any faulty electronic unit injectors. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove".
Install new electronic unit injectors. Refer to Disassembly and Assembly, "Electronic Unit Injector - Install".
Repeat the automatic "Cylinder Cutout Test". If the fault is still apparent, remove the replacement electronic unit injector and install the original electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove" and Disassembly and Assembly, "Electronic Unit Injector - Install".
Proceed to Test Step 10.
Result: All injectors are OK.
Contact the Dealer Solutions Network (DSN).