TM 5-2420-230-24-2
KSB Electrical Solenoid Style - General Information
Section 5 - Fuel System - Group 05
Page 5-8
B Series Shop Manual
VE Pump Timing Advance Principles (With Electrical Solenoid KSB Installed)
The KSB introduces a new fuel line (1), Figure 2, which routes fuel from the relief port (2) of the pressure regulator
valve (3) to the plunger end (6), Figure 3, of the electrical solenoid, bypassing the normal return passage (6), Figure
With the key switch on, current flows from the key switch line to the 90F normally closed intake manifold switch
to the 12V electrical KSB solenoid (see Figure 2). When the engine starts the pressure regulating valve (3) attempts
to regulate fuel pressure as before (without KSB) but the fuel from the relief port (2) now meets a `dead end' at
the plunger of the KSB solenoid (6), Figure 4. With the key switch on, the plunger moves outward and closes off
the flow of the fuel (8), Figure 4. This action hydraulically locks (closes) the pressure regulator slider valve (4), Figure
Housing pressure (5), Figure 2, is not regulated because the pressure regulator valve (3) is inoperable and so the
pressure continues to increase. This action fully advances the timing. The timing remains fully advanced until the
plunger (6), Figure 4, is opened and fuel is allowed to drain through fuel drain flow path (8), Figure 4.
When the intake manifold temperature reaches 90F, the 90F normally closed IMT switch opens and voltage is
no longer applied to the KSB solenoid (10). With no voltage applied to the KSB solenoid (13), fuel pressure
overcomes the plunger force and pushes the plunger back to open the fuel drain flow path (8).
Fuel from the relief port of the pressure regulating valve now has a drain path (8), Figure 4, past the KSB solenoid
plunger (6), Figure 4 (which is now open) to the drain. The pressure regulator valve resumes normal operation and
the injection timing is regulated accordingly.
The electrical solenoid style KSB is also equipped with a pressure relief valve (7), Figure 3. If the engine is taken
to high idle with the KSB solenoid plunger in the closed position (6), Figure 3, housing pressure can increase
enough to rupture the fuel pump housing. The pressure relief valve (7), Figure 3, will pop off its seat before this
occurs, however. At a pressure of 4 bar (60 psi), the pressure relief valve (7), Figure 3, opens and allows fuel to
drain through an alternate flow path (9), Figure 3.
L-306
