TM 5-3805-280-24-2
Fuel System Operation and Tests
115
for injection. The excessive fuel flows through the
A pressurizing valve is located at each outlet in the
63
pressure regulating valve back to the suction side of
pump head where the pressure line leading to the fuel
the transfer pump. A very small amount of this surplus
injection nozzle is connected. After injection, the
fuel escapes through the top of the governor housing.
pressure valve closes again, and with its small relief
piston, draws in a quantity of fuel from the pressure
To obtain the best possible performance over the
line.
entire speed range, the fuel injection pump is fitted
with an automatic, hydraulically operated speed
A pressurizing valve is located at each outlet in the
advance (L). This speed advance is preset at the
pump head where the pressure line leading to the fuel
factory. The speed advance adjusts timing of the fuel
injection nozzle is connected. After injection, the
injection pump in relation to engine speed and load.
pressure valve closes again, and with its small relief
piston, draws in a quantity of fuel from the pressure
The light load advance is standard on Model DP203
line.
pumps and optional on DP201 pumps.
The resulting relief in the pressure line causes a quick
A cold advance switch is optional on these pumps.
and firm closing of the nozzle valve. This prevents fuel
The switch consists of a housing to which is fitted a
spring-loaded piston assembly, a "wax motor", and a
spring-loaded ball valve. It is fitted at top of the spring
The quantity of fuel which is needed at any given
end of the auto advance housing.
regulated by a metering valve. The metering valve is
IMPORTANT: Remember that all adjustments to
controlled by the speed control rod and throttle lever
the injection pump, except for slow
(B), and by the governor inside the governor housing
idle, MUST BE carried out on a test
(A). In the "NO-FUEL" ("OFF") position, the metering
bench by a specialist injection pump
valve completely cuts the supply of fuel from supply
repair station only. Internal
pump to the rotor.
adjustments in the field are not
permitted, as this pump is a sealed
At slow idle speed or under full load, the supply pump
unit.
feeds more fuel to the metering valve than is needed
RG,115,JW7693 1924NOV972/2
13-590