ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 006-020   Fuel Inlet Restriction

• Obtain a 1.09-mm [0.043-in] orificed diagnostic fuel line, Part Number 3164621. This tool can also be constructed. Refer to Procedure 006-003 in Section 6.
• Obtain a container suitable for collection of fuel that exits the diagnostic fuel line. A 19-liter [5-gal] bucket is recommended.

Install a 1/8-inch NPT Compuchek™ diagnostic fitting, Part Number 3042618, at the inlet to the fuel injection pump (Cummins® Accumulator Pump System only).

Attach the 1.09-mm [0.043-in] orificed diagnostic fuel line at the fuel injection pump cam housing Compuchek™ fitting. Route this hose into a collection container or into the fuel tank.

Attach a 0 to 762 mm-Hg [0 to 30 in-Hg] vacuum gauge at the gear pump inlet Compuchek™ port.

CAUTION  Use caution when disconnecting or removing fuel lines, replacing filters and priming the fuel system. The fuel and fuel filters must be discarded in accordance with local environmental regulations.

Automotive and Industrial Applications

Obtain a 1.09-mm [0.043-in] orificed diagnostic fuel line, Part Number 3164621.

Obtain a pressure gauge adapter, Part Number 4918324.

Obtain fuel line connector fitting, Part Number 3972088.

Obtain a container suitable for collection of fuel that exits the diagnostic fuel line. A 19-liter [5-gal] bucket is recommended.

Install a pressure gauge adapter, Part Number 4918324. Use fuel line connector fitting, Part Number 3972088, at the inlet to the gear pump.

Install a vacuum gauge that has a range of at least 0 to 762 mm-Hg [0 to 30 in-Hg] onto the pressure gauge adapter.

Install an M10 Compuchek™ fitting, Part Number 3824842, at the fuel filter head.

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.

Attach the 1.09-mm [0.043-in] orificed diagnostic fuel line at the fuel filter head Compuchek™ fitting. Route this hose into a collection container or into the vehicle fuel tank.

CAUTION  Use caution when disconnecting or removing fuel lines, replacing filters and priming the fuel system such 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.

Cummins® Common Rail Fuel System

Attach a 0 to 762 mm-Hg [0 to 30 in-Hg] vacuum gauge at the Compuchek™ port at the OEM fuel inlet connection.

All Applications Except Marine

Operate the engine at high idle and measure the inlet vacuum.

Marine Applications

Operate the engine at rated rpm and measure the inlet vacuum.

If the inlet restriction is excessive, look for the root cause:

• Suction side fuel filters plugged
• Fuel heater valves restricted
• ECM cooling plate plugged
• ECM cooling plate check valve restricted
• OEM fuel lines pinched or restricted
• Fuel tank stand pipes restricted.

NOTE: Do not leave Compuchek™ fittings installed on the suction side of the gear pump. A Compuchek™ fitting on the suction side of the gear pump can allow air to enter the fuel flow, resulting in performance problems.

• Disconnect all diagnostic test fittings and install all components removed during testing.

• Disconnect the vacuum gauge from the Compuchek™ fitting. Leave the Compuchek™ fitting installed.