Injection will stop (see position 3) when fuel
Constant bleed valve (4) lets approximately 9
outlet (E) is lifted above the top edge of sleeve (D)
gallons of fuel per hour go back to fuel tank (7).
by camshaft (4). This movement lets the fuel that
This fuel goes back to fuel tank (7) through return
is above, and in, plunger (B) go through fuel outlet
line for constant bleed valve (3). This flow of fuel
(E) and return to the fuel injection pump housing.
removes air from housing (14) and also helps to
cool the fuel injection pump. Check valve (D)
When the sleeve (D) is raised on plunger (B), fuel
makes a restriction in this flow of fuel until the
outlet (E) is covered for a longer time, causing
pressure in housing (14) is at 8 3 psi (0.6 ± 0.2
more fuel to be injected in the engine cylinders. If
sleeve (D) is low on plunger (B), fuel outlet (E) is
covered for a shorter time, causing less fuel to be
The main components of a fuel injection pump
in the sleeve metering fuel system are barrel (A),
plunger (B), and sleeve (D), Plunger (B) moves up
The fuel inlet (6) and nozzle tip (13) are parts of
and down inside the barrel (A) and sleeve (D).
the nozzle body (11). Valve (8) is held in position
Barrel (A) is stationary while sleeve (D) is moved
by spring force. Force of the spring is controlled
up and down on plunger (B) to make a change in
by pressure adjustment screw (3). Locknut (4)
the amount of fuel for injection.
holds pressure adjustment screw (3) in position.
The lift of valve (8) is controlled by lift adjustment
When the engine is running, fuel under pressure
screw (2), Locknut (10) holds lift adjustment
from the fuel transfer pump goes in the center of
screw (2) in position, Compression seal (7) goes on
plunger (B) through fuel inlet (C) during the down
nozzle body (11).
stroke of plunger (B), Fuel can not go through fuel
outlet (E) at this time because it is stopped by
The compression seal goes against inlet fitting
sleeve (D), (see position 1),
(6) and prevents the leakage of compression from
the cylinder. Carbon dam (12), at the lower end of
Fuel injection starts (see position 2) when
nozzle body (11), prevents the deposit of carbon in
plunger (B) is lifted up in barrel (A) enough to
the bore in the cylinder head.
close fuel inlet (C). There is an increase in fuel
pressure above plunger (B), when the plunger is
lifted by camshaft (4). The fuel above plunger (B)
is injected in to the engine cylinder.
FUEL INJECTION NOZZLE
1. Cap. 2. Lift adjustment screw. 3. Pressure adjustment
screw. 4. Locknut for pressure adjustment screw. 5. O-ring seal.
6. Fuel Inlet. 7. Compression seal. 8. Valve. 9. Orifice (four).
10. Locknut for lift adjustment screw. 11.
Nozzle body. 12. Carbon dam. 13. Nozzle tip.
Fuel, under high pressure from the fuel injection
pump goes through the hole in fuel inlet (6). The
fuel then goes around valve (8), fills the inside of
nozzle body (11) and pushes against the valve
guide. When the force made by the pressure of the
FUEL INJECTION SEQUENCE
fuel is more than the force of the spring, valve (8)
will lift. When valve (8) lifts, fuel under high pres-
1, 2, 3. Injection stroke (position) of a fuel Injection
sure will go through the four .0128 in. (0.325 mm)
pump. 4. Injection pump camshaft. A, Barrel. 0. Plung-
orifices (9) into the cylinder. When the fuel is sent
er. C. Fuel Inlet. D, Sleeve. E. Fuel outlet. F, Lifter.