Operation - Yanmar MP series Service Manual

FUEL INJECTION NOZZLE
FUEL INJECTION NOZZLE
Operation
High pressure fuel from the fuel injection pump
flows through the high pressure pipe into the oil
passage in the nozzle housing and enters the
nozzle body reservoir.
When the fuel reaches the specified pressure, it
pushes open the nozzle valve (held down by spring
pressure) and is injected into the combustion
chamber at high pressure. lnjection nozzle opening
pressure is adjusted using shims to increase or
decrease the spring pressure on the nozzle valve.
(See Opening Pressure Adjustment on page 7-8)
As fuel passes through the nozzle, it is atomized to
mix uniformly with the air in the combustion
chamber. How well the fuel is mixed with high
temperature air directly affects combustion
efficiency, engine performance and fuel economy.
Note: Fuel injection nozzles must be kept in top
condition to maintain performance and
operating efficiency.
The nozzle valve is automatically closed by the
nozzle spring pressure at the end of the fuel
injection pump stroke.
Unused fuel between the nozzle valve and nozzle
body flows from the hole above the nozzle spring
through the fuel return fitting and back into the fuel
tank.
1. Fuel Return 4. Nozzle Spring
Fitting Seat
2.
Nozzle Housing
5.
Fllter
3. Nozzle Spring (Non-serviceable)
Figure 7-2
1. Reservoir Port 4. Nozzle Body
2.
Nozzle Valve
5.
Injection Port
3. Fuel Reservoir 6. Spray Angle
Figure 7-3
YAMMAR.
MP
series service Manual