Yanmar 1GM User Manual page 144

Chapter Seven
fuel Injection and Governor Systems
This chapter describes operation of the fuel injection
and governor systems and service procedures. Refer to
Chapter Two for troubleshooting procedures. Refer to
Chapter Three for maintenance procedures. Refer to
Chapter Five for a description ofdiesel engine operation.
Tables 1-3 are located at the end of this chapter.
WARNING
Serious fire hazards always exist around
diesel fuel. Do not allow any smoking in ar-
eas wherefuel is present. Always have afire
extinguisher, rated for fuel and electrical
fires, on hand when refueling or servicing
any part ofthe fuel system.
WARNING
Fuel emerges from the injector and
high-pressure fuel fittings with sufficient
force to penetrate the skin, which may cause
blood poisoning. Wear goggles and cover
exposed skin when working on high-pressure
components.
FUEL INJECTION FUNDAMENTALS
Engine operation is described under Diesel Engine
Fundamentals in Chapter Five.
The major components ofthe diesel fuel system are the
fuel tank, fuel filters, injection pump and injection noz-
zle(s) (Figure 1). A feed (transfer) pump moves fuel from
the fuel tank through the filters to the fuel injection pump.
Governor operation is described in Governor System in
this chapter.
Fuel Injection Pump
The fuel injection pump forces fuel into the fuel injec-
tor(s), which direct fuel into the engine combustion cham-
ber. The pump raises fuel pressure to approximately
17000 kPa (2540 psi), while also controlling the time and
amount of fuel injected.
The diesel injection pumps used on the engines covered
in this manual operate on the plunger and cam principle.
Refer to Figure 2 and Figure 3. A rotating cam in the en-
gine causes a plunger in the fuel injection pump to move
in a cylinder and pump fuel to the injector nozzle. A deliv-
ery valve and spring establish the beginning and ending of
injection while also maintaining residual pressure in the
injection line. The plunger is designed to alter fuel flow
when it is rotated. Fuel control is achieved by moving the
fuel control rack, which rotates the fuel plunger pinion
and plunger.