48556 Mercruiser BUSHING , Reducer (.250 to .125)

Probable Causes
Diagnostic codes
Air intake and exhaust system
Fuel supply
Transfer Pump Inlet Regulator (TPIR)
Electric Fuel Lift Pump (EFLP)
Return fuel lines
Throttle position sensor
CAN data link
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 Warranty Report and the Product Status Report with 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. Air Intake and Exhaust System
A. Check the air filter restriction indicator, if equipped.
B. Ensure that the air filter is clean and serviceable.
C. Check the air intake and exhaust systems for the following defects:
Blockages
Restrictions
Damage to lines or hoses
Air intake and exhaust system
Result: The air filter is blocked.
Repair: Install a new air filter. Check that the fault has been eliminated.
Result: The air intake or exhaust system is blocked or damaged.
Repair: Repair the air intake or exhaust system. Check that the fault has been eliminated.
Result: The air intake and exhaust system are not blocked or damaged.
Proceed to Test Step 3.
3. 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 lines that are restricted.
F. Check that the Electric Fuel Lift Pump (EFLP) is operating. If the EFLP is suspect, refer to Troubleshooting, "Relay - Test (Electric Fuel Lift Pump)".
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 EFLP. Replace the primary and secondary fuel filters. Verify that the repair eliminated the fault.
Proceed to Test Step 14.
Result: The fuel quality is OK.
Proceed to Test Step 4.
Illustration 1 g03750256
Transfer Pump Inlet Regulator (TPIR) components
(1) Transfer Pump Inlet Regulator (TPIR)
(2) TPIR return port
Illustration 2 g02355128
Minimum TPIR flow rate in a 12 VDC system
Illustration 3 g02355130
Minimum TPIR flow rate in a 24 VDC system
Table 2
Troubleshooting Test Steps Values Results
4. Transfer Pump Inlet Regulator (TPIR) Flow Test
Refer to Illustration 1.
A. Disconnect the TPIR return line from the drain port on the TPIR. Install a suitable blanking cap on the open port in the TPIR return line.
B. Connect a temporary drain line to the drain port on the TPIR.
C. Place the end of the temporary drain line into a suitable calibrated container.
D. With the isolator switch in the ON position but the engine not running, use a suitable multimeter to measure the input voltage to the EFLP. Record the reading.
E. With the isolator switch in the ON position but the engine not running, measure the fuel flow from the temporary drain line.
F. Refer to Illustration 2 or 3 for the minimum acceptable flow rate.
G. Remove the temporary drain line from the drain port on the TPIR. Connect the TPIR return line to the TPIR.
TPIR flow rate
Result: The fuel flow is greater than the minimum limit.
Proceed to Test Step 6.
Result: The fuel flow is less than the minimum limit.
Proceed to Test Step 5.
Illustration 4 g02527498
Minimum EFLP flow rate in a 12 VDC system
Illustration 5 g02527518
Minimum EFLP flow rate in a 24 VDC system
Table 3
Troubleshooting Test Steps Values Results
5. EFLP Flow Test at the Primary Fuel Filter Inlet
A. Make sure the keyswitch is in the OFF position.
B. Disconnect the fuel inlet connection from the primary fuel fi