Thermo King 002008, Manual

Page: 65 / 155

Engine Maintenance
65
Fuel Solenoid System
The fuel solenoid is located on the end of the
injection pump. It contains two coils: the pull-in
coil, and the hold-in coil. The pull-in coil draws
approximately 35 to 45 amps at 12 volts. The
hold-in coil draws approximately 0.5 amps at
12 volts.
The pull-in coil must be energized to move the
injection pump governor linkage to the fuel on
position. Once the injection pump governor
linkage has been moved to the fuel on position,
the hold-in coil will keep it in fuel on position
until the 8D circuit is de-energized. The pull-in
coil must be de-energized after a few seconds to
keep it from being damaged.
A fuel solenoid timer is used to control the fuel
solenoid pull-in coil. The fuel solenoid timer
consists of a small PC board that contains some
electrical components, a four pin wire connector,
and one removable relay. The relay is called the
fuel solenoid relay. The fuel solenoid timer is
mounted inside the control box.
Fuel Solenoid Timer Operation
The fuel solenoid hold-in coil is connected to the
8D circuit. The fuel solenoid relay coil is also
connected to the 8D circuit and it is grounded
through the fuel solenoid timer. The fuel solenoid
pull-in coil is connected to the 2A circuit through
the normally open contacts of the fuel solenoid
relay when the fuel solenoid relay is energized.
When the 8D circuit is energized, it supplies
power to the fuel solenoid hold-in coil and to the
fuel solenoid relay coil. The hold-in coil is
energized and remains energized as long as there
is power on 8D. The fuel solenoid relay is
energized momentarily by the fuel solenoid timer
when the 8D circuit is first energized. After
approximately 2.5 seconds, the fuel solenoid timer
de-energizes the fuel solenoid relay by opening
the circuit to ground.
During the time the fuel solenoid relay is
momentarily energized, the fuel solenoid pull-in
coil is energized by the 2A circuit through the
normally open contacts of the fuel solenoid relay
and the 8DP circuit.
When power is removed from the 8D circuit the
fuel solenoid hold-in coil is de-energized, and the
fuel solenoid resets.
1. Fuel Solenoid
Figure 35: Fuel Solenoid Location
1
ARA112
1. Four Pin Connector
2. Fuel Solenoid Relay (FSR)
Figure 36: Fuel Solenoid Timer
AGA337
1 2