DIESEL FUEL SYSTEM COMPONENTS
Q4-21.
Which of the following statements best de-
scribes the purpose of a governor on a diesel
LEARNING OBJECTIVES: Identify the
engine?
components of a diesel engine fuel system.
1. To regulate the amount of air entering the
Recognize the purpose of the components of a
cylinder
diesel engine. Identify preheating devices used
2. To regulate the amount of fuel going to the
on diesel engines.
carburetor
The diesel fuel system is similar to the gasoline
3. To prevent the engine from overspeeding
system in tank and fuel line construction only. Each
and allow it to meet changing load condi-
manufacturer has their own method of transferring the
tions
fuel and creating the high pressure required for
4. To prevent the engine from wet stacking
injection of the fuel into the cylinders.
and allow the engine to reach a higher
rpm (revolutions per minute) during a
FUEL TANKS
fault condition
The diesel fuel tank is mounted directly on the
Q4-22.
What two factors determine the type of gov-
chassis of SE equipment because of its weight (when
ernor to be used on a diesel engine?
filled) and to prevent movement of the tank when the
1. The type of fuel and the type of load
equipment is operated over rough terrain. Its location
2. The type of fuel and the degree of control
also depends on the type of equipment and the
desired
equipment's use. Fuel tank caps are usually threaded
3. The degree of control desired and the
internally and screw onto the tank filler pipe. Most fuel
operating environment
caps are equipped with a sealing gasket and vent hole.
4. The type of load and the degree of control
desired
FUEL GAUGES
Q4-23.
A governor that can maintain any desired
The electric gauges used on diesel fuel tanks are the
speed between idle and maximum speed is
same type as used in the gasoline fuel system. Some
classified as what type of governor?
manufacturers use a bayonet-type gauge that is
1.
A speed-limiting governor
permanently attached to the filler cap of the fuel tank or
2.
A spring-loaded centrifugal governor
installed under the fuel cap. These are graduated and
3.
A variable-speed governor
the fuel level is checked by the same method as oil in an
4.
A mechanical governor
engine.
Q4-24.
A governor that is designed to keep the engine
FUEL FILTERS
from exceeding a specified maximum speed or
dropping below a specified minimum speed is
Fuel filters are built into the fuel supply systems of
classified as what type of governor?
diesel engines to filter any abrasive impurities that may
1.
A speed-limiting governor
be in the fuel. These impurities may have been difficult
2.
A spring-loaded centrifugal governor
to eliminate during the process of refining, or they may
3.
A variable-speed governor
enter the fuel tank through careless refueling. Whatever
4.
A mechanical governor
the source, these impurities must be removed to protect
the closely fitted parts in the pumps and nozzles.
Q4-25.
Devices that bring an overspeeding engine to
a complete stop by shutting off the fuel or air
Most diesel engines have two filters in the fuel
to the engine are known as what type of de-
supply system. The primary (coarse) filter is usually
vices?
located between the supply tank and the fuel supply
pump, and the secondary (fine) filter between the fuel
1.
Overspeed governors
supply pump and the injection pump. Additional
2.
Overspeed trips
filtering elements are frequently installed between the
3.
Overspeed limiters
injection pump and the nozzle.
4.
Overspeed actuators
4-26
