3056E Industrial Engine Caterpillar

Test the Fuel Injection Nozzles

Perform the following procedures in order to determine if a fuel injection nozzle does not work correctly.

Bench test the fuel injection nozzles at a temperature of 18° to 20 °C (64° to 70 °F).

1. Run the engine at low idle.

2. Loosen the nut for fuel supply line at the fuel injection nozzle on cylinder number 1. Listen for the low idle to decrease or become rough. Tighten the nut for the fuel supply line on cylinder number 1. Perform this test on each cylinder.

3. The fuel injection nozzle is faulty when the fuel supply line is loosened and the following events occur:

   • The engine rpm does not decrease.

   • The engine does not idle roughly.

   Remove the fuel injection nozzle for additional testing.

   Note: If leakage occurs at the nut for fuel supply line , make sure that fuel supply line and the nut for fuel supply line are correctly aligned with the inlet connection of fuel injection nozzle . Do not tighten the nut for fuel supply line on the high pressure fuel line more than the recommended torque. If the nut is tightened more, the fuel line may become restricted or the threads of the fuel injection nozzle and the nut may be damaged.

Cleaning of the Fuel Injection Nozzles

Before a fuel injection nozzle is tested, remove any loose carbon from the tip of the fuel injection nozzle. Do not use abrasive material or a wire brush in order to clean the nozzle.

The fuel injection nozzle is not a serviceable part. Disassembling or adjusting the nozzle will violate the standards for emissions.

Note: Extra care should be used in handling the fuel injection nozzle in order to prevent damage to the nozzle tip. A scratch or a burr could cause needle leakage or spray distortion. Dirt in the orifices of the nozzle tip can damage engine components. Dirt can also distort the spray pattern of the nozzle.

Pressure Test

Show/hide table

Ensure that you wear eye protection at all times during testing. When fuel injection nozzles are tested, test fluids travel through the orifices of the nozzle tip with high pressure. Under this amount of pressure, the test fluid can pierce the skin and cause serious injury to the operator. Always keep the tip of the fuel injection nozzle pointed away from the operator and into the fuel collector and extension.

Illustration 1	g00910915
5P-4150 Nozzle Testing Group (1) 5P-7448 Adapter (2) Fuel injection nozzle (3) 6V-2170 Tube assembly (4) 1U-8857 Extension (5) 8S-2270 Fuel collector (6) 8T-5313 Filter

1. Connect fuel injection nozzle (2) to the tooling that is shown in Illustration 1.

   The spray from the fuel injection nozzle must be directed into the 1U-8857 Extension (4) and the 8S-2270 Fuel collector (5).

   Opening pressure for the injectors is 25338 ± 345 kPa (3675 ± 50 psi).

   If the opening pressure is not within the range of the setting which is given in the table, the fuel injection nozzle must be replaced.

   Use clean 6V-6068 Calibration Fluid when the fuel injection nozzles are tested. The calibration fluid is equivalent to SAE J-967 (ISO 4113) oil.

2. Close the gauge protector valve. Close the shutoff valve. Open the pump isolator valve. In order to flush the fuel injection nozzle, operate the nozzle tester for 10 to 15 strokes at a rate of approximately 60 strokes per minute.

3. Open the gauge protector valve. Slowly increase the pressure until the valve in the fuel injection nozzle opens. Note the highest pressure indication on the dial indicator before the pointer moves to 0 kPa (0 psi). This highest pressure indication is the opening pressure of the fuel injection nozzle. The opening pressure is defined when valve needle is lifted from the valve seat.

4. If the opening pressure is not within the range of the setting that is given in the table, the fuel injection nozzle must be replaced.

Back Leakage Test

1. Connect fuel injection nozzle (2) to the tooling. Refer to Illustration 1 for more information.

   Position the fuel injection nozzle so that the direction of the fuel spray is into the 1U-8857 Extension (4) and the 8S-2270 Fuel collector (5).

2. Pump the pressure to about 1030 kPa (150 psi) below the opening pressure of the fuel injection nozzle.

   Release the handle. When the pressure begins to decrease, note the time that is required for the pressure to decrease to approximately 0 kPa (0 psi). If the fuel injection nozzle is not faulty, the time will not be less than 5 seconds or more than 45 seconds.

3. Look for any leakage. If leaks are visible, make sure that the components are tightened to the correct torque. Replace the fuel injection nozzle if there is excessive fuel leakage.

   Note: Do not overtighten the components in order to stop the leakage. Instead, a pressure test on the fuel injection nozzle must be conducted. Repeat Steps 1 and 2 in the "Pressure Test" procedure. This test may force any foreign particles out of the nozzle.

4. If the pressure decreases to 0 kPa (0 psi) in less than 5 seconds, too much fuel is leaking around the valve needle. The valve needle or the fuel injection nozzle must be replaced in order to correct the problem.

Fuel Injection Nozzle and Seat Test

1. Refer to Illustration 1 in order to connect fuel injection nozzle (2) to the tooling.

   Position the fuel injection nozzle so that the fuel spray is directed into the 1U-8857 Extension (4) and the 8S-2270 Fuel Collector (6).

2. Pump the pressure of the nozzle tester to approximately 1030 kPa (150 psi) below the opening pressure of the fuel injection nozzle. A drop of fuel should not form on the tip of the fuel injection nozzle for at least ten seconds. A light dampness is acceptable. If the results of the tests are not acceptable, clean the fuel injection nozzle. After you clean the fuel injection nozzle and fuel leakage occurs, the nozzle must be replaced.

Test the Spray Pattern

The pressure adjustment must be correct before you test the spray pattern.

Show/hide table

Ensure that you wear eye protection at all times during testing. When fuel injection nozzles are tested, test fluids travel through the orifices of the nozzle tip with high pressure. Under this amount of pressure, the test fluid can pierce the skin and cause serious injury to the operator. Always keep the tip of the fuel injection nozzle pointed away from the operator and into the fuel collector and extension.

Illustration 2	g00322083
Correct spray pattern for a fuel injection nozzle

1. Refer to Illustration 1 in order to connect fuel injection nozzle (2) to the tooling.

   Position the fuel injection nozzle so that the fuel spray is directed into the 1U-8857 Extension (4) and the 8S-2270 Fuel Collector (5).

2. Close the gauge protector valve and the shutoff valve. Open the pump isolator valve.

3. Quickly pump the nozzle tester and look at the spray pattern when the fluid begins to flow through the orifices of the fuel injection nozzle.

   The spray, which flows from all of the orifices, must have the same pattern. The fuel injection nozzle is faulty if there is a difference in the vertical patterns or a difference in the horizontal patterns. Refer to the correct spray pattern in Illustration 2.