Guardian Technologies 4270 manual Engine Governor, Fuel Injection Pump, Fuel Nozzles/Injectors

Section 5

ENGINE DC CONTROL SYSTEM

The positive (+) battery cable (13) attaches to one of the outer posts of the contactor along with Wire 13 for the DC supply to the fuse (F1). The starter cable (16) attaches to the remaining outer post. Attached to the small 2 lugs are Wires 56 and 0. When the start/stop switch is set to start, the circuit board delivers battery voltage to the contactor coil via Wire 56. The contac- tor energizes and its contacts close. Battery voltage is then delivered from the positive battery cable, across contacts and to the starter motor via Wire 16.

ENGINE GOVERNOR

Amechanical, all-speed governor is used on the diesel engine. It is housed in the gear case. A fly- weight movement is transmitted to the injection pump control rack by way of the slider, control lever and link. A spring is attached to the arm and the tension lever. The spring regulates flyweight movement. By changing the set angle of the governor lever, tension on the tension lever spring is changed. In this man- ner, engine speed can be regulated by the governor lever.

The generators A/C output frequency is directly pro- portional to engine speed. Low governor speed will result in a reduced A/C frequency and voltage, and high governor speed will produce an increased fre- quency and voltage.

FUEL INJECTION PUMP

CONTROL RACK

SHIM

INJECTOR PUMP

Figure 5-8. – Fuel Injection Pump

The fuel injection pump is mounted on the side of the engine and rides on a three-lobe camshaft. The lobes on the camshaft press the bottom of the pump, which mechanically opens the fuel path to deliver fuel to the fuel injectors. Timing for the fuel injector pump is determined by the distance between the camshaft lobes and the pump. This distance is regulated by metal shims. If the shim space is incorrect, the fuel pressure will be incorrect and combustion will not occur. When the fuel injector pump is removed for maintenance, be sure to reassemble with the same number of shims. The engine governor controls the fuel injector pump by linkage connecting the two.

FUEL NOZZLES/INJECTORS

Fuel supplied by the injector pump is delivered to the nozzle holder and to the nozzle body. When fuel pressure is sufficient to compress the spring, fuel is supplied from the nozzle and into the combustion chamber. Due to the high pressure of fuel being ejected from the nozzle, there is no safe test. If faulty fuel is suspected and a clogged injector pump was diagnosed, the replacement of the injector nozzles would be needed.

INJECTOR

CAP

INSERT

GASKET

Figure 5-9. – Fuel Injectors
VALVE	VALVE	FULLY
CLOSED	OPEN	OPEN

Figure 5-10. – Fuel Injector Nozzles

GLOW PLUGS

The glow plug consists of a thin coiled heat-wire that is encased in sintered magnesium oxide powder and enclosed by a stainless steel sheath. One end of the wire is welded to the sheath and the other end is welded to the center electrode. When voltage is applied to the center electrode, it heats the heat-wire, which in turn, heats the combustion chamber.

Glow plugs are connected in parallel. For that rea- son, if one plug fails open, the other plugs will contin- ue to operate. However, loss of one plug will increase the possibility of the heat-wire melting open in the remaining plugs.

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