Ford Taurus Manual page 882

ELECTRONIC FUEL INJECTION (EFI)
diaphragm. Control of the fuel system is maintained through the Electronic Engine
Control (EEC) power relay and the EEC-IV control unit, although electrical power
is routed through the fuel pump relay and an inertia switch. The fuel pump relay
is normally located on a bracket somewhere above the Electronic Control
Assembly (ECA) and the inertia switch is located in the storage compartment.
Tank-mounted pumps can be either high or low-pressure, depending on the
model.
The inertia switch opens the power circuit to the fuel pump in the event of a
collision. Once tripped, the switch must be reset manually by pushing the reset
button on the assembly. Check to make sure that the inertia switch is reset
before diagnosing power supply problems to the fuel pump circuit.
The fuel injectors used with the EFI system are an electromechanical (solenoid)
type designed to meter and atomize fuel delivered to the intake ports of the
engine. The injectors are mounted in the lower intake manifold and positioned so
that their spray nozzles direct the fuel charge in front of the intake valves. The
injector body consists of a solenoid actuated pintle and needle valve assembly.
The control unit sends an electrical impulse that activates the solenoid, causing
the pintle to move inward off the seat and allow the fuel to flow. The amount of
fuel delivered is controlled by the length of time the injector is energized (pulse
width), since the fuel flow orifice is fixed and the fuel pressure drop across the
injector tip is constant. Correct atomization is achieved by contouring the pintle at
the point where the fuel enters the pintle chamber.
Exercise care when handling fuel injectors during service. Be careful not
to lose the pintle cap and always replace old O-rings with new ones to
assure a tight seal. Never apply direct battery voltage to test a fuel
injector.
The injectors receive high pressure fuel from the fuel manifold (fuel rail)
assembly. The complete assembly includes a single, preformed tube with six
injector connectors, a mounting flange for the fuel pressure regulator, mounting
attachments which locate the fuel manifold assembly and provide fuel injector
retention and a Schrader® quick-disconnect fitting used to perform fuel pressure
tests.
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18.11.2005