Gasoline and Diesel Fuel Injection: Operation ... - Pearson Canada

696 CHAPTER 29
FUEL INJECTION PUMPS
Two types of mechanical injection pumps are common
with conventional systems: the in-line and the rotary.
In-line Injection Pumps (4-Cycle)
In-line pumps are usually found on large trucks and
older passenger car/light truck applications. See Figure
29–47.The pump is driven at one-half the engine speed,
which means the injection-pump camshaft makes one
complete revolution for each two turns of the engine.
When the pump cam lobe pushes up on the cam follower
and plunger, the fuel above the plunger is put under
very high pressure. See Figure 29–48. This highpressure
fuel opens the delivery valve spring, which allows
fuel to move through steel lines to the injectors,
where it is supplied to the engine. See Figure 29–49.
SAFETY
TIP
Never check for fuel leaks by running
your hand over the lines—a high pressure
leak could penetrate your skin, enter the
blood stream and cause poisoning.
It is good practice, instead, to move a piece of light
coloured cardboard along the lines, checking visually for
signs of liquid fuel on the cardboard. See Figure 29–50.
Figure 29–47 An in-line
diesel injection pump.
(Courtesy Ford Motor Co.)
Figure 29–48 A diesel fuel injection pump: start of injection. (Courtesy Ford Motor Co.)