fuel pump JAGUAR S TYPE 1999 1.G Powertrain Manual

V6 EngineAJ-V6/AJ28
29
D.303.1215
FUEL RAIL AND LOWER INTAKE MANIFOLD
Fuel Supply
D.303.1215
EFT Sensor
De-pressurisation
Valve
IP Sensor
Fuel System
Returnless Fuel System
The returnless fuel system is a one way system
which delivers fuel to the engine without the
requirement for fuel to be returned to the tank.
When a return line is used, the effects of fuel
pressurisation, de-pressurisation and engine heat
on the returning fuel causes extra vapour to be
generated in the tank. With increasing regulatory
controls on evaporative emissions, this is an
undesirable condition and elimination of a fuel
return line provides significant benefits.
The in-tank fuel pump supplies fuel and regulates
pressure to the injectors under control of the PCM
and the rear electronic module (REM) and a
pressure regulator is not therefore required on the
engine fuel rail. To provide feedback for closed
loop control, an injector pressure (IP) sensor on
the fuel rail detects the pressure differentialbetween the fuel and the intake manifold and the
engine fuel temperature (EFT) sensor monitors
fuel temperature. Analogue signals from both
sensors are sent to the PCM to indicate the
pressure of the fuel and to detect whether it has
reached the vapourisation point. In response to
the sensor inputs and driver or load demands, the
PCM requests the pump system to vary the fuel
flow; in particular, fuel pressure will always be
increased to avoid vapour formation and to
maintain flow through the injectors.
Fuel pump control is further described in the
ÔS-TYPE IntroductionÕ Technical Guide.
Fuel Rail and Lower Intake Manifold
The fuel injectors are seated in two lower intake
manifolds, made of a lightweight plastic
composite material, which are fitted between the
Fuel Rail
Lower Intake
Manifold

V8 Engine AJ-V6/AJ28
56
Fuel Injection
Returnless Fuel System
The function and operation of the returnless fuel
system is the same as that fitted to the V6 engine
but with different fuel pipework to suit the V8
layout. The air assisted, top fed, fuel injectors are
supplied from two separate rails joined by an
interconnecting cross-over pipe (similar to AJ27)
with a single common feed from the fuel tank.
The fuel rail assembly is removeable. An engine
fuel temperature (EFT) sensor and injector
pressure (IP) sensor provide feedback to the PCM
to control the fuel pump flow rate (see ÔS-TYPE
IntroductionÕ Technical Guide). Note that the EFT
sensor is not in direct contact with the fuel (ÔdryÕ
type sonser).
J.303.1390
FUEL RAIL ASSEMBLY
IP Sensor
EFT Sensor
J.303.1390