C4.4 (Mech) Industrial Engine Fuel System Pressure - Test Caterpillar

Illustration 1	g00928705
(A and B) Fuel outlet (1) Fuel priming pump (2) Fuel filter

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

Check the Function of the Fuel Priming Pump

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

2. Connect two lengths of 5/16 inch rubber hose to 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 priming pump until a constant flow of fuel is running from the outlet for the supply for the fuel injection pump.

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

4. 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), repair the pump or 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 the outlet for the supply for the fuel injection pump (B).

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

3. Start the engine and run the engine at idle for two minutes in order to remove any trapped air.

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

   Delphi DP310

   Idle ... 25 kPa (3.63 psi)

   High Idle ... 25 kPa (3.63 psi)

   Note: Maximum pressure for the fuel injection pump is 75 kPa (10.88 psi).

5. Turn the key to the RUN position for three minutes in order to energize the fuel priming pump. Do not start the engine. Then turn the key to the OFF position.

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 fuel filter housing (2) does not leak.