TM 5-3805-258-24-1
FUEL SYSTEM
SYSTEMS OPERATION
The 8N7005 Fuel Injection Nozzle can not be
is pushed thru the outlet check valve (3) and out
disassembled and no adjustments can be made.
pump outlet port (8). Fuel also moves thru pump
inlet port (6) and inlet check valve (7) to fill the area
FUEL TRANSFER PUMP
below piston (2). The pump is now ready to start a
Models 950BNSCE and 950BSCE
new cycle.
The fuel transfer pump is a piston pump that is
moved by a cam (eccentric) on the camshaft for the
fuel injection pump. The transfer pump is located on
the bottom side of the fuel injection pump housing.
FUEL TRANSFER PUMP (START OF DOWN STROKE)
(ARROWS INDICATE FUEL FLOW DIRECTION)
1. Push rod. 2. Piston. 3. Outlet check valve. 4. Pumping
check valve.
5. Pumping spring. 6. Pump inlet port.
7. Inlet check valve. 8. Pump outlet port.
When the fuel injection pump camshaft turns, the
cam moves push rod (1) and piston (2) down. As the
piston moves down, inlet check valve (7) and outlet
check valve (3) close. Pumping check valve (4) opens
and allows the fuel below the piston to move into the
area above the piston. Pumping spring (5) is com-
pressed as the piston is pushed down by push rod (1).
As the fuel injection pump camshaft continues to
turn, the cam no longer puts force on push rod (1).
Pumping spring (5) now moves piston (2) up. This
causes pumping check valve (4) to close. Inlet check
valve (7) and outlet check valve (3) will open. As the
piston moves up, the fuel in the area above the piston
FUEL TRANSFER PUMP (START OF UP STROKE)
(ARROWS INDICATE FUEL FLOW DIRECTION)
1. Push rod. 2. Piston. 3. Outlet check valve. 4. Pumping
check valve. 5. Pumping spring. 6. Pump inlet port.
7. Inlet check valve. 8. Pump outlet port.
FUEL TRANSFER PUMP
Models 950BNS and 950BS
The fuel transfer pump is a two-piston pump that
is moved by a cam (eccentric) on the camshaft for the
fuel injection pump. The transfer pump is located on
the right side of the fuel injection pump housing.
When the camshaft turns, the cam lifts push rod
(10) up. The push rod lifts large piston (9), push
plate (6) and small piston (3). As the pistons move
up, inlet check valve (5) and outlet check valve (8)
close. Pumping check valve (7) in the large piston
opens and fuel goes through the holes in the bottom
of the large piston and fills the passages and chamber
between the bottom of the large piston and outlet
check valve (8). As small piston (3) moves up, the
pressure of the fuel above the piston increases and
flows out of the pump through outlet (4).
As the camshaft continues to turn, the cam lowers
push rod (10) down. Pumping spring (2) pushes
small piston (3), push plate (6) and large piston (9)
down. When the piston moves down, inlet check valve
(5) and outlet check valve (8) open. Pumping check
3-5
