88579 Mercury SPRING, COMPRESSION

Table 1
Diagnostic Codes for the Fuel Priming Pump
CDL Code Description Comments
1627-5 Fuel Pump Relay : Current Below Normal The code is logged.
The engine Electronic Control Module (ECM) detects an open circuit at the fuel pump relay for 60 seconds.
The ECM detects a short to battery voltage for the fuel pump relay for 60 seconds.
The ECM can only detect this condition when the output driver is not activated.
1627-6 Fuel Pump Relay : Current Above Normal The code is logged.
The engine ECM detects a short circuit for the fuel pump relay.
The ECM can only detect this condition when the output driver is activated. The ECM is used to energize the fuel pump relay. The fuel pump relay controls battery power to the fuel priming pump. The circuit that is for battery power uses a 15 amp fuse for circuit protection. Automatically Priming the Fuel SystemWhen the keyswitch is turned to the ON position, the engine ECM uses an automatic fuel priming strategy to pressurize the low-pressure fuel system. The engine ECM also powers the fuel priming pump during engine cranking.An override parameter on Caterpillar Electronic Technician (ET) allows the technician to activate the fuel priming pump. The test is only functional when the engine speed is zero rpm. Access the test via the "Override Parameters" screen on Cat ET.
Illustration 1 g02222554
Typical schematic for the fuel priming pump
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g02133295
Location of the ECM connectors for the fuel priming pump
(1) J1/P1 ECM connectors
Illustration 3 g02222613
Location of the fuel priming pump (right engine view)
(2) Fuel priming pump
Thoroughly inspect connectors (1). Also, thoroughly inspect the connectors for pump (2). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 4 g02156857
Terminal locations for the fuel priming pump at the P1 ECM connector
(P1-13) Fuel priming pump relay
(P1-18) Return
Illustration 5 g01210818
Terminal locations at the fuel priming pump relay
(Terminal 1) Unswitched +Battery
(Terminal 2) Control circuit from the ECM
(Terminal 3) Return from the ECM
(Terminal 5) Power to the fuel priming pump
Illustration 6 g01155187
Terminal locations at the connector for the fuel priming pump
(Terminal 1) Power to the fuel priming pump
(Terminal 2) Return
Check the torque of the allen head screws for each of the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from the connectors for the electric fuel priming pump to the ECM. Expected Result:All connectors, pins, and sockets are coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The connectors and the wiring appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or the wiring are not OK.Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Verify that the problem is resolved.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Cat ET to the service tool connector.
Restore power to the ECM.
Turn the keyswitch to the ON position.
Select diagnostic tests from Cat ET.
Select the "Override Parameters" screen on Cat ET.
Activate the override for the fuel pump relay.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active.
Deactivate the override for the fuel pump relay.
Again, monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active, but a problem is suspected in the circuit for the fuel priming pump. Proceed to Test Step 6.
Not OK - A -5 diagnostic code is active at this time. Proceed to Test Step 4.
Not OK - A -6 diagnostic code is active at this time. Proceed to Test Step 3.Test Step 3. Create an Open at the Connector for the Fuel Pump Relay
Remove power from the ECM.
Turn the keyswitch to the OFF position.
Disconnect the connector from the fuel pump relay.
Restore power to the ECM.
Turn the keyswitch to the ON position.
Select diagnostic tests from Cat ET.
Select the "Override Parameters" screen on Cat ET.
Activate the override for the fuel pump relay.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active.
Deactivate the override for the fuel pump relay.
Again, monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.Expected Result:A -5 diagnostic code is now active for the fuel pump relay.Results:
OK - A -5 diagnostic code became active after disconnecting the connector for the fuel priming pump.Repair: Temporarily install a new fuel pump relay. Verify that there are no active diagnostic codes for the fuel pump relay. Clear any logged diagnostic codes.STOP
Not OK - A -6 diagnostic code remains active. There is a short between the connector for the fuel pump relay and the ECM. Proceed to Test Step 5.Test Step 4. Create a Short at the Connector for the Fuel Pump Relay
Remove power fro