OPERATION OF 9L7883 FUEL INJECTION NOZZLE

FUEL SYSTEM

SYSTEMS OPERATION

(90N1-90N6120)

The main components of a fuel injection pump

The compression seal goes against inlet fitting

in the sleeve metering fuel system are barrel (A),

(7) and prevents the leakage of compression from

plunger (B), and sleeve (D). Plunger (B) moves up

the cylinder. Carbon dam (13), at the lower end of

and down inside the barrel (A) and sleeve (D).

nozzle body (12), prevents the deposit of carbon in

Barrel (A) is stationary while sleeve (D) is moved

the bore in the cylinder head.

up and down on plunger (B) to make a change in

the amount, of fuel for injection.

Fuel, under high pressure from the fuel injection

pump goes through the hole in fuel inlet (7). The

When the engine is running, fuel under pressure

fuel then goes around valve (9), fills the inside of

from the fuel transfer pump goes in the center of

nozzle body (12) and pushes against valve guide

plunger (B) through fuel inlet (C) during the down

(6). When the force made by the pressure of the

stroke of plunger (B). Fuel can not go through fuel

fuel is more than the force of spring (4), valve (9)

outlet (E) at this time because it is stopped by

will lift. When valve (9) lifts, fuel under high

sleeve (D), (see position 1).

pressure will go through the four .0128 in. (0.325

mm) orifices (10) into the cylinder. When the fuel

Fuel injection starts (see position 2) when

is sent to the cylinder, the force made by the

plunger (B) is lifted up in barrel (A) enough to

pressure of the fuel in the nozzle body will become

close fuel inlet (C). There is an increase in fuel

less. The force of spring (4) will then be more than

pressure above plunger (B), when the plunger is

the force of the pressure of the fuel in the nozzle

lifted by camshaft (4). The fuel above plunger (B)

body. Valve (9) will move to the closed position.

is injected in to the engine cylinder.

Injection will stop (see position 3) when fuel

Valve (9) is a close fit with the inside of nozzle

outlet (E) is lifted above the top edge of sleeve (D)

tip (14), this makes a positive seal for the valve.

by camshaft (4). This movement lets the fuel that

is above, and in, plunger (B) go through fuel outlet

When the fuel is sent to the cylinder, a small

(E) and return to the fuel injection pump housing.

quantity of fuel will leak by valve guide (6). This

fuel gives lubrication to the moving parts of the

When the sleeve (D) is raised on plunger (B), fuel

fuel injection nozzle This fuel then goes through a

outlet (E) is covered for a longer time, causing

leak off boot at the top of nozzle body (12) and is

more fuel to be injected in the engine cylinders. If

returned to the fuel tank.

sleeve (D) is low on plunger (B), fuel outlet (E) is

covered for a shorter time, causing less fuel to be

FUNCTION OF FUEL JUNCTION BLOCK

injected.

OPERATION OF 9L7883 FUEL INJECTION NOZZLE

The fuel inlet (7) and nozzle tip (14) are parts of

the nozzle body (12). Valve (9) is held in position

by force of spring (4). Force of spring (4) is

controlled by shims (11). The lift of valve (9) is

controlled by lift adjusting screw (1). Locknut (2)

holds lift adjusting screw (1) in position. Compres-

sion seal (8) goes on nozzle body (12).

CONNECTIONS FOR FUEL LINES AT

THE FUEL JUNCTION BLOCK

1. Connection for constant bleed line to fuel tank. 2.

Connection for fuel supply line to fuel tank. 3. Connection

for fuel supply line to fuel filter. 4. Fuel injunction block. 5.

Connection for bleed line for fuel injection nozzles to fuel

FUEL INJECTION NOZZLE

tank. 6. Connection for constant bleed line to housing for

1. Lift adjusting screw. 2. Locknut. 3. Pressure screw.

fuel injection pumps. 7. Connection for bleed line for fuel

4. Spring. 5. Spring seat. 6. Valve guide. 7. Fuel

injection nozzles on right side of engine. 8. Connection for

inlet. 8. Compression seal. 9. Valve. 10. Orifices

bleed line for fuel injection nozzles on left side of engine. 9.

four). 11. Shims. 12. Nozzle body. 13. Carbon dam.

Tee.

14. Nozzle trip.