C9.3B Engines Caterpillar

The high-pressure fuel pump has two sides. This procedure checks the pumping capacity of each side.

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Illustration 1	g06258416
High-pressure fuel pump connector

1. Refer to Illustration 1. Unplug the harness connector (1).

2. Crank the engine for 10 seconds. Record the rail pressure.

3. Record the rail pressures in Table 1. Put the higher rail pressure in the left column. Put the lower rail pressure in the right column. Perform the steps in the Table.
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   Table 1

   Testing the Sides of the High-Pressure Fuel Pump
   	Higher Rail Pressure	Lower Rail Pressure
   Step 1 Record the rail pressures.
   Step 2 Multiply the higher rail pressure by 0.7.		N/A
   If the lower rail pressure is greater than the value in Step 2, the high-pressure fuel pump passes this test.

   Refer to the following example. In this example, the pump failed the test. The lower rail pressure is too low.

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   Table 2

   Example of Testing the Sides of the High-Pressure Fuel Pump
   	Higher Rail Pressure	Lower Rail Pressure
   Step 1 Record the rail pressures.	16 MPa (2300 psi)	10 MPa (1450 psi)
   Step 2 Multiply the higher rail pressure by 0.7.	11 MPa (1600 psi)	N/A
   If the lower rail pressure is greater than the value in Step 2, the high-pressure fuel pump passes this test.

4. If the lower rail pressure is greater than the value in Step 2 of the table, the high-pressure fuel pump passes this test. If the lower rail pressure is less than the value in Step 2 of the table, replace the high-pressure fuel pump.