C3.3 Industrial Engine Caterpillar

Illustration 1	g01235017
(A and B) Fuel outlet (1) Fuel transfer pump (2) Fuel filter

The pressure test measures the output pressure of the fuel transfer pump. Low fuel pressure and starting difficulty may be indications of faults with the fuel priming pump.

Check the Function of the Fuel Transfer Pump

1. Make a note of the location of the fuel lines from the fuel transfer pump. Remove the two lines from fuel outlets (A) and (B) .

2. Connect two suitable lengths of 5/16 inch rubber hose to fuel outlets (A) and (B). Place the hoses into a suitable container that is capable of holding 3 L (3.17 qt) of fuel.

3. Energize the fuel transfer pump until a constant flow of fuel is running from the outlet for the supply for the fuel injection pump.

   Note: The flow from fuel outlet (B) for the return to the fuel tank will have a slower flow rate.

4. Use a suitable tool in order to measure the combined flow of both outlets with a stopwatch. Fuel flow should be a minimum of 2 L/min (0.53 US gpm).

5. If the combined flow is less than 2 L/min (0.53 US gpm), replace the pump.

6. Reconnect the outlet lines in the correct positions.

7. Start the engine and check for any leakage of fuel or air from the fuel lines.

Check the Function of the Pressure Regulator

1. Remove the fuel line from fuel outlet (A) for the supply to the fuel injection pump.

2. Install a suitable pipe with a tap for a pressure gauge. Connect a 0 to 80 kPa (0 to 12 psi) pressure gauge.

   Note: One end of the pipe must be blanked.

3. Energize the fuel transfer pump for two minutes in order to remove any trapped air.

4. Record the pressure reading at high idle. The minimum pressure reading should be the following values:

   All Fuel Injection Pumps

   Low idle ... 25 kPa (3.6 psi)

   High idle ... 25 kPa (3.6 psi)

   Note: The maximum pressure for the fuel injection pump at idle speed or rated speed is 75 kPa (10.9 psi).

5. Reconnect the fuel line. Energize the fuel transfer pump for two minutes in order to remove any trapped air.

Check for the following issues if the pressures are outside of the above specifications.

• All electrical connections are installed correctly.

• There are no leaks in the fuel lines or connections.

• The O-ring on the fuel filter housing (2) does not leak.