The fuel system supplies clean fuel to injection pump and nozzles, and circulates unused fuel back to the tank.
An electric fuel transfer pump pumps low-pressure fuel to the fuel filter/water separator and then to the fuel injection pump inlet. Fuel from the transfer pump flows to the fuel shutoff valve in the top of the fuel filter/water separator. The injection pump then directs high-pressure fuel through the injector lines to the fuel injector nozzles for combustion. Excess fuel from the injection pump is combined with leak off fuel from the injectors, through a junction fitting and is routed through the top of the secondary filter base, back to the fuel tank. An air bleed hole in the return line automatically purges air from the return line.
If the machine runs out of fuel, or after servicing fuel strainer and water separator, air must be bled from the fuel strainer and water separator. Make sure that fuel shutoff valve is ON.
Turn the key switch ON. Let the electric fuel transfer pump run (you should hear clicking sound) for 30 seconds to purge the air from the fuel system.
The engine speed is controlled by the throttle lever. The throttle rod is connected to the injection pump governor control lever. The fuel shutoff solenoid controls the injection pump shutoff shaft. When the solenoid is retracted (key in the START or ON position), the engine can run. When the key is turned off, return springs on the shutoff shaft, extend the solenoid, moving the shutoff linkage to the shutoff position. The solenoid also closes if the machine is operated in an unsafe condition.
The injection pump meters fuel as determined by the governor and delivers it at high pressure to the injectors.
The injection nozzle prevents flow until high pressure is reached, then opening the valve and spraying atomized fuel into the combustion chamber. Injection lines contain trapped fuel whenever injection is not taking place.
A small amount of fuel leaks past the nozzle valve to lubricate the fuel injection nozzle. This leakage combines with excess fuel from the injection pump and is returned to tank. Any air in the fuel system is bled out with return fuel to the fuel tank.