Centinel System – Repair Manual – 005-045   Fuel Lift Pump

Inspect the engine harness, the lift pump power connector, the lift pump relay power connector, and the lift pump relay pins for the following:

• Loose connector
• Corroded pins
• Bent or broken pins
• Pushed back or expanded pins
• Moisture in or on the connection
• Missing or damaged connector seals
• Dirt or debris in or on the connector pins
• Connector shell broken
• Wire insulation damage
• Damaged connector locking tab.

See the service manual for the proper procedure for replacing or repairing connectors, pins, or harnesses.

CAUTION  Do not use probes or leads other than Part Number 3822758 and Part Number 3822917. The connector will be damaged. The leads must fit tightly in the connector without expanding the pins in the connector.

Check for an open circuit in the fuel lift pump return circuit.

Disconnect the 2-pin fuel lift pump power connector at the fuel lift pump.

Disconnect the fuel lift pump relay power connector where the OEM harness connects to the engine harness.

Measure the resistance of the fuel lift pump return between these two connectors.

The resistance must be 10 ohms or less.

If the resistance is greater than 10 ohms, repair or replace the engine harness.

CAUTION  Do not use probes or leads other than Part Number 3164572. The connector will be damaged. The leads must fit tightly in the connector without expanding the pins in the connector.

Check for an open circuit in the fuel lift pump relay return line.

Measure the resistance from the fuel lift pump relay return pin in the engine harness relay connector to engine block ground.

The resistance must be 10 ohms or less.

If the resistance is greater than 10 ohms, repair or replace the engine harness ground.

Measure the resistance of the fuel lift pump relay.

Measure the resistance between the fuel lift pump relay signal pin and the fuel lift pump relay return pin on the relay.

The resistance must be between 70 and 80 ohms.

If the resistance is not between 70 and 80 ohms, replace the fuel lift pump relay.

CAUTION  Do not use probes or leads other than Part Number 3822758 and Part Number 3822917. The connector will be damaged. The leads must fit tightly in the connector without expanding the pins in the connector.

Remove the fuel lift pump power connector at the fuel lift pump.

Turn the keyswitch to the ON position.

Measure the voltage between the fuel lift pump supply pin and the fuel lift pump return pin on the harness connector.

The voltage must be battery voltage.

If voltage is not present, check the fuse on the fuel lift pump relay supply line. Replace if necessary.

If the voltage is not correct, disconnect the 2-pin connector between the OEM harness and the engine harness that supplies the fuel lift pump relay with unswitched battery power.

Measure the voltage at the 2-pin connector on the OEM harness.

The voltage must be battery voltage.

If voltage is not present, repair or replace the OEM wiring or contact a Cummins® Authorized Dealer.

Check the fuel lift pump relay for proper operation.

Unplug the fuel lift pump relay from the engine harness connector.

Check the voltage at the fuel lift pump relay supply pin.

The voltage must be battery voltage.

If voltage is not present, recheck the fuses and the OEM/engine harness for shorts and open circuits.

With the keyswitch in the ON position, measure the voltage at the fuel lift pump relay signal pin on the engine harness relay connector.

A measurement of 12-VDC must be indicated.

If 12-VDC is not indicated, check the ECM for the proper calibration and contact a Cummins® Authorized Repair Location.

Unplug the fuel lift pump relay from the engine harness connector.

Connect the 2-pin fuel lift pump power connector to the fuel lift pump.

Insert a jumper wire between the fuel lift pump relay supply pin and the fuel lift pump supply pin in the engine harness relay connector.

If the fuel lift pump is functioning correctly, the fuel lift pump will operate.

If the lift pump does not operate when using the jumper wire, Refer to Procedure 019-396 in the CM870 Electronic Control System, Signature™ and ISX Engines Troubleshooting and Repair Manual, Bulletin 4021334, for replacing the lift pump.

Turn the ignition switch to the ON position to activate integrated fuel system mounted, automotive, or industrial timing module priming pumps. Repeat if necessary.

Measure the fuel pressure at the gear pump inlet Compuchek™ fitting.

If 69 kPa [10 psi] or greater is indicated, the lift pump is operating correctly.

If less than 69 kPa [10 psi] is indicated, check the pressure while drawing fuel from a bucket.

WARNING  Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

CAUTION  If the unit has recently switched to Bio-diesel or Ultra Low Sulfur diesel and has a fuel leak, the entire lift pump must be replaced, not only the gasket.

Remove or disconnect the following:

• Battery cables. Refer to Procedure 013-009.
• Engine wiring harness from the fuel lift pump.
• EGR differential pressure sensor tubes. Refer to Procedure 011-026.
• EGR differential pressure sensor. Refer to Procedure 019-043 in the CM870 Electronic Control System, Signature™ and ISX Engines Troubleshooting and Repair Manual, Bulletin 4021334.

NOTE: The fuel lift pump is bolted to a mounting plate and must be removed as an assembly.

Remove the four capscrews.

Remove the fuel lift pump.

Remove and discard the gasket.

Disconnect the fuel pump wiring harness and the power supply connections at the starter.

Tag the wires for location at installation.

Disconnect the fuel outlet line from the top of the Integrated Fuel System Module (IFSM).

Disconnect the fuel inlet line from the rear of the IFSM.

Remove the fuel lift pump assembly mounting capscrews and the fuel lift pump assembly.

Disconnect the ground wire from the cylinder block.

Disconnect the fuel pump wiring harness and the power supply connections at the starter.

Tag the wires for location at installation.

Disconnect the fuel inlet and outlet lines from the fuel pump.

Remove the mounting capscrews and mounting plate.

Remove the fuel pump assembly.

Remove the large internal hex plug from the fuel pump.

Remove the filter screen and the gasket.

Clean the mounting surfaces.

Inspect the fuel lift pump mounting plate for leaks, cracks, and other damage.

If any damage is found, replace the fuel lift pump.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

WARNING  Some solvents are flammable and toxic. Read the manufacturer’s instructions before using.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Use solvent to clean the parts.

Flush debris from the filter screen.

Dry with compressed air.

Clean the mounting surfaces.

Inspect the fuel lift pump mounting surface for cracks or other damage.

If any damage is found, replace the fuel lift pump.

Use an Allen wrench to check for free movement of the check valve.

Replace the check valve assembly, if damaged.

CAUTION  The fuel lift pump is extremely sensitive to debris. A small amount of debris in the lift pump can cause the lift pump to fail, causing it to need replacement. Only service the lift pump in clean areas and use care not to allow debris into the system.

CAUTION  The lift pump contains many loose parts. Use care when removing the lift pump body from the adaptor and keep the lift pump vertical.

This step includes the method for removing and installing the fuel lift pump gasket.

Remove the three bolts that connect the adapter to the lift pump body.

Replace the fuel lift pump gasket.

Connect the adapter and lift pump assembly.

Tighten the bolts.

Install a new gasket between the fuel lift pump mounting plate and the IFSM.

Install the fuel lift pump and the four capscrews.

Tighten the capscrews.

To verify the lift pump is not leaking, turn the keyswitch to the ON position with the engine off, operate the lift pump for three minutes, and check for leaks.

Install the fuel lift pump assembly and mounting capscrews.

Be sure both copper washers are in place on the top fitting when installing the fuel outlet line.

Install two new sealing washers on the fuel outlet line.

Install the fuel outlet line.

Install the fuel inlet line to the IFSM.

Connect the wiring harness connectors to the starter.

Install a new filter sealing ring.

Install the clean filter.

Install the large plug with a new o-ring.

Tighten the plug.

Install the fuel lift pump, mounting plate, and capscrews.

Install the fuel inlet and outlet lines.

Install the ground wire to the cylinder block.

Install the power supply connections to the starter.

Install or connect the following:

• EGR differential pressure sensor. Refer to Procedure 019-043 in the CM870 Electronic Control System, Signature™ and ISX Engines Troubleshooting and Repair Manual, Bulletin 4021334.
• EGR differential pressure sensor tubes. Refer to Procedure 011-026.
• Engine wiring harness to the fuel lift pump.
• Battery cables. Refer to Procedure 013-009.
• Prime the fuel system. Refer to Procedure 005-016 in Section 5.
• Start the engine and check for leaks.