Fuel Injection System Components - Triumph TR7 Owner's Manual

EMISSION AND EVAPORATIVE LOSS CONTROL SYSTEMS
Fuel Injection System Components
Fuel is drawn from a tank al the rear of the vehicle and
pressurised to approximately 2,5 kgf/cm
2
(36 Ibl/in
2 )
by an
electric fuel pump located
benea~h
the car floor. The fuel
pump will only operate when the ignition and/or the starter
motor circuits are energised, From this pump fuel passes
through fuel filters located in the engine compartment (Rover
3500) or beneath the car floor (TR models} to a pressure
regulator, the spring chamber of which is connected to the
engine intake manifold. As a result, the difference between
the intake manifold pressure and the fuel pressure is held
constant, excess fuel being returned to the fuel tank via an
anti-surge pot
A fuel rail links the pressure regulator with the fuel injectors,
one injector being fitted into each inlet manifold spur. The
injectors may be either ·open' or 'closed· and are solenoid
operated, The injector solenoids are energised through a
relay actuated by the ignition circuit and are pulsed to ·open·
by the electronic control unit
(LeU.)
completing the circuit
to 'ground:' When 'open'the injectors spray fuel into the Inlet
manifold to be drawn into the engine cylinders at the next
induction stroke of the working cycle.
Therefore there needs to be no fixed relationship between the
injector timing and the engine ignition or valve timing.
The injectors are programmed to ·open' in banks of four. in
unison, twice per engine operating cycle (two revolutions).
On eight cylinder engines the two banks of four injectors
operate alternately, The time that the injectors are ·open'
governs the amount of fuel supplied to the engine and this
open' time is computed by the electronic control unit from
the input it receives from various sensors
Fig,4 TR7 Fuel injection system components
Key
to Fig, 4
(1) Cold start injector
(2) Injectors
(3) Fuel rail
(4) Cold start injector - fuel feed pipe
(5) Fuel pressure regulator
(6) Return line to fuel tank
(7) Pipe to plenum chamber
(8) Thermo time switch
5