PRINCIPLES GASOLINE/DIESEL FUEL SYSTEMS - OD1620 - LESSON 2/TASK 2
type, operated by an engine-based camshaft. Fuel flows from a connection at
the top of the fuel pump shutdown valve, through a supply line, into the
lower drilled passage in the cylinder head at the front of the engine. A
second drilling in the head is aligned with the upper injector radial groove
to drain away excess fuel. A fuel drain at the flywheel end of the engine
allows return of the unused fuel to the fuel tank. There are four phases of
(a) Metering (figure 54, view A, on the following page).
phase begins with the plunger just beginning to move downward when the
in the cup, the check ball stops the fuel from flowing backwards, and the
fuel begins to be pressurized.
The excess fuel flows around the lower
annular ring, up the barrel, and is trapped there.
(b) Preinjection (figure 54, view B, on the following page). The
plunger is almost all the way down, the engine is almost at the end of the
compression stroke, and the fuel is being pressurized by the plunger.
(c) Injection (figure 54, view C, on the following page).
plunger is almost all the way down, the fuel is injected out the eight
(d) Purging (figure 54, view D, on the following page).
plunger is all the way down, injection is finished, and the fuel is flowing
into the injector, around the lower annular groove, up a drilled passageway
in the barrel, around the upper annular groove, and out through the fuel
drain. The cylinder is on the power stroke. During the exhaust stroke, the
plunger moves up and waits to begin the cycle all over again.
g. PBS Distributor Injection System.
(1) Overall System Operation (figure 55 on page 93).
distributor system uses a pump that sends measured charges of fuel to each
injector at a properly timed interval. The difference in the PSB system is
that the charges of fuel are sent directly from the pump at the high
pressure that is necessary for injection. This