ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 005-025   Fuel Pump Gear Pump

The gear pump shaft incorporates a double seal. The first seals oil in the fuel pump cam housing; the second seals fuel in the gear pump. If either seal fails, fluid will drip from the weep hole. The weep hole is located near the gear pump mounting flange on the inboard side (toward the engine block).

A gear pump gasket seals oil at the gear pump to cam housing interface.

Measuring Gear Pump Pressure with the Engine Cranking (useful if engine will not start).

1. Install a pressure gauge at the on engine fuel filter head (M10 x 1.5 Compuchek™ fitting, Part Number 3824842).

NOTE: If there is not enough clearance to install the female Compuchek™ fitting, Part Number 3824842, an adapter fitting, Part Number 3932302, and an 1/8-NPT male Compuchek™ fitting, Part Number 3377244, may be used to aid accessibility.

1. Monitor the gear pump pressure while the engine is cranking.

Minimum Gear Pump Pressure at Cranking

If the gear pump pressure is lower than 105 kPa [15 psi] during cranking, make sure that the engine cranking speed is at least 150 rpm. Make sure that the lift pump pressure during cranking is at least 35 kPa [5 psi]. Refer to Procedure 005-045 in Section 5.

NOTE: For optional test points on the fuel system, a banjo pressure gauge adapter can be constructed.

Construction of Banjo Pressure Gauge Adapter

A banjo-style pressure gauge adapter can be used to measure pressure or vacuum at any point in the low-pressure fuel system where a banjo bolt exists at a fuel line.

The ISC and ISL engines with high-pressure common rail fuel systems use a M12 x 7/16-inch banjo bolt connection. This tool can be used for measurement of drain line restriction (pressure) at the fuel drain manifold.

Make a banjo bolt flow adapter tool by drilling and tapping the hex face of an M12 x 7/16-inch banjo bolt, Part Number 3903035 or similar banjo bolt.

Drill and tap the banjo bolt to the size of the Compuchek™ fitting (or other hose union) being used (example 1/8-inch NPT Compuchek™ fitting, Part Number 3377244, or M10 Compuchek™ fitting, Part Number 3824842).

Assemble the banjo pressure gauge adapter as follows.

1. Install the Compuchek™ fitting, or other type fitting, in the hexagonal face of the banjo bolt.
2. Attach a hose or pressure gauge to the banjo pressure adapter.

Measuring Gear Pump Pressure at Rated Condition

1. Install a M10 x 1.5 Compuchek™ fitting, Part Number 3824842, at the diagnostic port on the outlet of the fuel filter head.
2. Construct a “T” adapter fitting using one quick-disconnect, Part Number 3376859, and two 1/8-inch NPT Compuchek™ fittings, Part Number 3042618.
3. Install a 0.043-inch orificed diagnostic fuel line (Part Number 3164621) at the outlet of the fuel filter head. Run the fuel hose back to the fuel tank.
4. Install a 0 to 1034 kPa [0 to 150 psi] pressure gauge at the “T” adapter fitting.

Operate the engine at high idle and observe the gear pump pressure.

If the gear pump pressure is low, check for excessive inlet vacuum. Refer to Procedure 006-020 in Section 6.

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.

WARNING  Depending on the circumstance, diesel fuel is flammable. Keep all cigarettes, flames, pilot lights, arcing equipment, and switches out of the work area and areas sharing ventilation to reduce the possibility of severe personal injury or death when working on the fuel system.

WARNING  Do not vent the fuel system on a hot engine; this can cause fuel to spill onto a hot exhaust manifold, which can cause a fire.

CAUTION  Use caution when disconnecting or removing fuel lines, replacing filters and priming the fuel system that fuel is not spilled or drained into the bilge area. Do not drop or throw filter elements into the bilge area. The fuel and fuel filters must be discarded in accordance with local environmental regulations.

• Disconnect the batteries. Refer to Procedure 013-009 in Section 13.
• Shut off the fuel supply. Refer to the OEM service manual.
• Clean any fuel, oil, and debris from the gear pump.
• Remove the fuel supply lines from the gear pump. Refer to Procedure 006-024 in Section 6.

Remove the four bolts that hold the gear pump to the fuel pump.

Remove the drive coupling if it remains attached to the rear of the fuel pump camshaft.

Remove the gear pump gasket.

Inspect the gear pump for damage.

NOTE: Gear pump coupling wear is normal. The gear pump should not be replaced due to coupling or shaft wear.

Install the drive coupling into the back of the high-pressure pump camshaft.

Insert the mounting bolts through the gear pump flange.

Install a new gasket onto the bolts.

Index the gear pump input shaft to engage the drive coupling and install the gear pump.

Install the four gear pump bolts and tighten.

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.

• Install the fuel supply lines. Refer to Procedure 006-024 in Section 6.
• Connect the batteries. Refer to Procedure 013-009 in Section 13.
• Open the fuel supply valve. Refer to the OEM service manual.
• Operate the engine and check for leaks.