36 SENR9977 Testing and Adjusting Section i02253606 Fuel System - Prime i02253617 Fuel System Pressure - Test If air enters the fuel system, the air must be purged before the engine can be started. Air can enter the fuel system when the following events occur: The fuel tank is empty or the tank has been partially drained during normal operation. The low pressure fuel lines are disconnected. A leak exists in the low pressure fuel system during engine operation. The fuel filter or the fuel pump is replaced. The high pressure fuel lines are disconnected. g01135042 Illustration 45 Use the following procedure in order to remove air from the fuel system:
(1) Fuel transfer pump (2) Fuel filter housing (3) Outlet for the supply for the fuel injection pump (4) Outlet for the return to the fuel tank 1. Remove the cover for the fuel injectors. The pressure test measures the output pressure of the fuel transfer pump. Low fuel pressure and starting difficulty may be indications of problems with the fuel transfer pump. 2. 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 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 the outlets (3) and (4).
2. Connect two lengths of 5/16 inch rubber hose to outlets (3) and (4). Place the hoses into a suitable container that is capable of holding 3.0 L (0.66 Imp gal) 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. g01135020 Illustration 44 (1) Connections for the high pressure fuel lines Note: The flow from the outlet for the return for the fuel tank will have a slower flow rate. 3. Loosen the connections for the high pressure fuel lines (1). 4. Operate the electric starter motor until fuel that is free of air comes from the connections. 4. Measure the combined flow of both outlets with a stopwatch.
Fuel flow should be a minimum of 2.0 L (0.44 Imp gal) per minute. 5. Tighten the connections for the high pressure fuel lines to a torque of 30 N·m (22 lb ft). 5. If the combined flow is less than 2.0 L (0.44 Imp gal) per minute, replace the fuel transfer pump. 6. Start the engine and check for leaks. 6. Reconnect the outlet lines in the correct positions. 7. Install the cover for the fuel injectors.