807172 Mercruiser FILTER, Fuel/Water Separator

An electrical fault can prevent the electronic unit injector from operating. An open circuit or a short circuit in the ECM that is unique to one electronic unit injector will prevent that electronic unit injector from operating. An open circuit or a short circuit in common wiring within the ECM can prevent the two electronic unit injectors that share that common wiring from operating. Injector 1 and injector 4 share common wiring within the ECM. Injector 2 and injector 3 share common wiring within the ECM.Perform this procedure under conditions that are identical to the conditions that exist when the fault occurs. Typically, faults with the injector solenoid occur when the engine is warmed up and/or when the engine is under vibration (heavy loads).These engines have Electronic Unit Injectors (EUI). The ECM sends a pulse to each injector solenoid. The pulse is sent at the correct time and at the correct duration for a given engine load and speed. The solenoid is mounted on top of the fuel injector body.If an open circuit is detected in the solenoid circuit, a diagnostic code is generated. The ECM continues to try to fire the injector. If a short circuit is detected, a diagnostic code is generated. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the fault is corrected.
Illustration 1 g06554513
Schematic of the circuit for the injector solenoids
Illustration 2 g02373637
Typical example of the harness connector for the fuel injectors
Illustration 3 g02373216
(1) Cylinder 3 injector supply
(2) Cylinder 2 injector supply
(16) Cylinder 1 injector supply
(17) Cylinder 4 injector supply
(31) Cylinder 3 injector return
(32) Cylinder 1 injector return
(46) Cylinder 2 injector return
(48) Cylinder 4 injector return
Electrical Shock Hazard. The electronic unit injectors use DC voltage. The ECM sends this voltage to the electronic unit injectors. Do not come in contact with the harness connector for the electronic unit injectors while the engine is operating. Failure to follow this instruction could result in personal injury or death.
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.
B. Thoroughly inspect the connectors at the injectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Inspect the terminals on the P1/J1 ECM connector and all other connectors associated with the injector solenoid circuits.
D. Perform a 30 N (6.7 lb) pull test on each of the wires in the ECM connector that are associated with injector solenoids.
E. Check the harness and wiring for abrasion and for pinch points from the injectors to the ECM.
Damaged wire or connector
Result: A damaged wire or damaged connector was found. A fuse is blown.
Repair: Repair the damaged wire or the damaged connector. Replace any blown fuses
Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
Result: All connectors, pins, and sockets are correctly connected and/or inserted and the harness is free of corrosion, of abrasion or of pinch points.
Proceed to Test Step 2.
2. Check for Active Diagnostic Codes
A. Connect the electronic service tool to the diagnostic connector.
B. Start the engine.
C. Allow the engine to warm up to the normal operating temperature.
D. Stop the engine.
E. Turn the keyswitch to the ON position.
Note: Wait at least 30 seconds for activation of the diagnostic codes.
F. Use the electronic service tool in order to verify if any of the diagnostic codes that are listed in Table 1 are active or recently logged.
Diagnostic codes
Result: An -5 diagnostic code is active or recently logged.
Note the cylinders that the codes are applicable to. Proceed