3306C Truck Engine Caterpillar

Testing Fuel Injection Nozzles

Note: See Special Instruction, SEHS7292, "Use of 5P-4150 Fuel Nozzle Tester 8S-2245 Kit" for more information.

Caterpillar Inc. recommends the use of Calibration Fluid (SAE J967) for testing the fuel injection nozzles. The temperature of the test fluid needs to be from 18° to 24°C (64° to 75°F).

Illustration 1	g00301875
5P-4150 Nozzle Testing Group (1) 5P-7448 Adapter (2) 8N-7005 Fuel Valve Nozzle (3) 6V-2170 Tube assembly (4) 6V-6993 Pressure Gauge (5) FT-1384 Extension (6) 6V-6989 Pressure Gauge (7) Gauge protector valve for 6V-6993 Gauge (8) 8S-2270 Fuel collector (9) Gauge protector valve for 6V-6989 Pressure Gauge (10) On/Off valve (11) Pump isolator valve

Illustration 2	g00314004
Extra Valve (12) Gauge protector valve must be in the OPEN position at all times.

Do not disassemble the fuel injection nozzle for cleaning or for adjustment. Use the following tests to determine if the nozzle's performance is acceptable:

• "Valve Opening Pressure Test"

• "Flush the Nozzle"

• "Tip Leakage Test"

• "Orifice Restriction Test"

• "Leakage Test for Air Purge Screw"

These tests follow immediately.

Performance Tests for the Fuel System

Preparing the Fuel Injection Nozzle for Testing

Illustration 3	g00314003
Removing a Carbon Dam (13) Fuel injection nozzle. (14) Carbon dam. (15) Seal.

Before fuel injection nozzle (13) can be tested, remove all loose carbon around the tip of the nozzle.

Illustration 4	g00314152
8S-2245 Cleaning Kit (16) 8S-2258 Cleaning Brush. (17) 6V-4979 Carbon Seal Installation Tool. (18) 8S-2250 Holding Tool .

Clean a fuel injection nozzle with 8S-2258 Cleaning Brush (16) .

1. Remove carbon dam (14) with needle nose pliers.

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NOTICE
Do not use a steel brush or wire wheel to clean the nozzle body or the nozzle tip. Use of these tools can cause a small reduction of orifice size, and this will cause a large reduction in engine horsepower. Too much use of a wire brush will also remove the coating that is on the fuel injection nozzle for protection.

2. Remove seal (15) from the nozzle.

3. Clean the groove for carbon dam's seal.

4. Clean the body of the nozzle below with a 8S-2258 Cleaning Brush (16).

5. Carefully remove the carbon, but avoid damage to the body of the fuel injection nozzle with the brush.

   Note: A change of the color in the area below the groove is normal. This does not affect the body of the fuel injection nozzle.

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Illustration 5	g00314154
Fuel Injection Nozzle (19) Air purge screw and seal.

6. Remove the air purge screw and seal (19) .

   Note: The air purge screw and the seal must be removed for all tests except for the "Leakage Test for Air Purge Screw".

Valve Opening Pressure Test (VOP)

Illustration 6	g00314156
Fuel Injection Nozzle (Test) (7) Gauge protector valve. (10) On/Off valve. (11) Pump isolator valve.

1. Install 6V-2170 Tube Assembly (3) to the tester.

2. Install fuel injection nozzle with 5P-7448 Adapter (1).

3. Position the hole for the air purge screw toward the tester. This hole should be in line with 6V-2170 Tube Assembly (3) .

   The fuel's spray pattern will be horizontal.

4. Point the fuel injection nozzle's tip downward.

   Make sure that this nozzle's tip extends into both the FT-1384 Extension (5) and the 8S-2270 Fuel Collector (8) .

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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.

Note: Place a shop towel around the upper part of the fuel injection nozzle. This shop towel should be used to absorb any fuel leakage.

5. Close on/off valve (10) .

6. Open pump isolator valve (11) .

7. Open gauge protector valve (7), and use the pump to create a slow increase in pressure. Continue operating the pump until the fuel injection nozzle begins to open.

8. Read the maximum gauge pressure at the instance when the test fluid flows from the fuel injection nozzle's tip.

   Note: While the pump isolator valve is opening, the pressure reading on the gauge can drop quickly. The check valve will make a noise at the same time. The gauge's pressure reading might remain constant when the check valve in the fuel injection pump opens.

   Note: The check valve can make noise when the check valve is in good operating condition. The check valve can also spray a coarse vapor from the nozzle's orifices in Step 8.

   If the opening pressure does not meet specifications, do not use the same fuel injection nozzle again. Review the specifications in Table 2.

Flush the Nozzle

1. Close gauge protector valve (7). Also, close on/off valve (10) .

2. Then, open pump isolator valve (11) .

   Note: Make sure that the fuel injection nozzle extends inside the top of FT-1384 Extension (5).

3. Operate the pump rapidly for three full strokes.

Tip Leakage Test

1. Use a clean cloth to remove all the fuel from the fuel injection nozzle's tip and from the body.

2. Place a clean cloth around the body of the fuel injection nozzle. Use this cloth to catch any fuel leakage from the air purge screw's hole.

   This will help prevent any fuel leakage from draining into the fuel injection nozzle's tip.

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Illustration 7	g00314156
Fuel Injection Nozzle that is Ready for Testing (7) Gauge protector valve. (10) On/Off valve. (11) Pump isolator valve.

3. Open gauge protector valve (7), and close on/off valve (10).

4. Then, open pump isolator valve (11) .

5. After you create a pressure of 1380 to 2000 kPa (200 to 290 psi) less than the opening pressure that was measured in the VOP Test, hold this pressure for 15 seconds. Count the number of drops that fall into the fuel collector.

6. Record the number of drops that fall. Compare the number of drops that are counted with the number in Table 3.
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   Table 3

   Tip Leakage Specification

   No more than 5 drops should fall in 15 seconds.

7. If the nozzle is not within the specifications, DO NOT USE the nozzle.

Orifice Restriction Test

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Illustration 8	g00314156
Fuel Injection Nozzle That Is Ready for Testing (7) Gauge protector valve. (10) On/Off valve. (11) Pump isolator valve.

1. Close gauge protector valve (7) and on/off valve (10) .

2. Then, open pump isolator valve (11) .

3. Point the tip of the fuel injection nozzle into the extension and toward the fuel collector.

   Position the hole for the air purge screw toward the tester. This hole should be in line with 6V-2170 Tube Assembly (3). After this positioning, the fuel injection nozzle should be 15 degrees from vertical, and the spray pattern will be horizontal.

4. Create a rapid pressure increase, and look at the orifice discharge when fluid begins to flow through the fuel injection nozzle.

   In fact, look at the shape of this discharge. There should be a similar discharge through all nine or six orifices. Any vertical change or any horizontal change indicates a worn nozzle. Review Illustrations 9 through 12.

Illustration 9	g00319183
A Good Nozzle That Can Be Used Again

Illustration 10	g00319184
Discharge of an Orifice with a Restriction

Replace this fuel injection nozzle.

Illustration 11	g00319185
Discharge of an Orifice with a Horizontal Distortion

Replace this fuel injection nozzle.

Illustration 12	g00319186
Discharge of an Orifice with a Vertical Distortion

Replace this fuel injection nozzle.

Leakage Test for Air Purge Screw

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Illustration 13	g00314154
Fuel Injection Nozzle (19) Air purge screw and seal.

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NOTICE
Do not tighten the air purge screw more than the listed torque amounts. The air purge screw or the seal can be damaged.

1. Install air purge screw and seal (19) into the fuel injection nozzle.

   Note: Refer to Specifications, "Fuel Injection Nozzles and Adapters" for information on torques.

2. Point the tip of the fuel injection nozzle into the extension and toward the fuel collector.

3. Close on/off valve (10) .

4. Open gauge protector valve (7) and pump isolator valve (11) .

5. Pump the tester until the fuel injection nozzle fills with test fluid and the pressure gauge shows 12800 to 14800 kPa (1850 to 2150 psi).

   Note: To attain a pressure of 12800 to 14800 kPa (1850 to 2150 psi), you might need to pump the tester for 15 strokes or for 20 strokes.

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   Table 4

   Specification for Air Purge Screw

   No leakage can occur between the air purge screw and the fuel injector nozzle's body.

6. If leakage occurs, follow this procedure:

   1. Replace the seal (15) .

   2. Inspect the seal face of the air purge screw for damage. Replace the air purge screw, if necessary.

   3. Retest the fuel injection nozzle. If leakage still occurs, the complete fuel injection nozzle needs to be replaced.

7. If no leakage occurs, follow this procedure:

   1. Continue using the same fuel injection nozzle, but replace the seal.
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   Illustration 14	g00319236
   Installing a Carbon Dam (14) Carbon dam. (15) Seal. (17) 6V-4979 Carbon seal tool .

   2. Also, install a new carbon dam in the nozzle's groove with a 6V-4979 Carbon Seal Tool (17) .

Fuel Injection Lines

Fuel from the Fuel Injection Pumps to the Fuel Injection Nozzles

Fuel from the fuel injection pumps flows to the fuel injection nozzle through fuel injection lines.

When fuel injection lines are disconnected, always place caps on the end and plugs on the end. This will keep the dirt out of the lines. When fuel injection lines are installed, make sure that all clamps and all dampers are returned to original positions.

The nuts that connect a fuel injection line to both the fuel injection nozzle and the fuel injection pump must be tightened to the correct torque.

If the nuts are not tightened to the proper torque, the following problems may occur:

• If the nut is loose, fuel will leak from the connection.

• If the nut is too tight, the inside diameter of the line will become smaller. This causes a restriction to the fuel flow in the fuel line.

Use a torque wrench and a 5P-0144 Fuel Line Socket to tighten the fuel injection line nut to a torque of 40 ± 7 N·m (30 ± 5 lb ft).

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Fuel injection lines that are bent, damaged, or rubbing against surfaces can leak and cause a fire. Replace any lines that are bent, or damaged when tightened to the correct torque. Correct or replace any lines that are rubbing when tightened to the correct torque.

Checking the Plunger and Lifter of an Injection Pump

Note: If the pump plunger is worn, good contact will not occur. A pump plunger must be replaced if the pump plunger is damaged. A lifter must also be replaced if the lifter is worn. There are no different sizes of spacers that are available so you can adjust the timing dimension of the fuel injection pumps. Since there is no possible adjustment to the timing dimension, no off-engine adjustment procedure for the engine lifter setting procedure is available.

If the pump plunger on the fuel injector is worn, the lifter may also be worn. If either of these conditions exists, good contact will not be possible. Replace the lifters soon after you see wear on the pump plunger. Also, replace lifters that show any signs of wear.

Illustration 15	g00319239
Wear Between the Lifter and the Pump Plunger (1) The contact surface of a new pump plunger and surface of a new lifter (2) The contact surface of a pump plunger with considerable wear and surface of lifter with considerable wear (3) Fast wear due to the new end of a pump plunger with poor contact against worn lifter

A fuel injection pump can send a good fuel flow, yet this fuel injection pump may not be a good pump. Wear on the bottom end of the pump plunger causes slow timing. When you test a used fuel injection pump with a long life, use a micrometer to measure the length of the pump plunger.

If the length of the pump plunger is shorter than the minimum, specified length, replace the fuel injection pump. Any amount that is below the specified length indicates that the pump plunger is worn. See Table 5 for more information on the Fuel Pump Plunger.

Also, look for wear at the top of the pump plunger. Check the operation according to the instructions in Testing and Adjusting, "Fuel Injection Test Bench".