Jaguar XJ (X350). Service manual — part 654

CAUTION: Make sure that any protective clothing worn is clean and made from

lint-free non-flocking material.

CAUTION: Make sure that clean non-plated tools are used. Clean tools using a

new brush that will not lose its bristles and fresh cleaning fluid, prior to starting work
on the vehicle.

CAUTION: Use a steel topped workbench and cover it with clean, lint-free non-

flocking material.

CAUTION: Make sure the workshop area in which the vehicle is being worked on

is as clean and as dust free as possible. Foreign matter from work on clutches, brakes or
from machining or welding operations can contaminate the fuel system and may result
in later malfunction.

NOTE:

Pneumatic vacuum gun

1. Using a new brush that will not lose its bristles, brush cleaning fluid onto the components
being removed and onto the surrounding area.


2. Using a pneumatic vacuum gun, remove all traces of cleaning fluid and foreign material.


3. Dispose of any used cleaning fluid and the brush after completing the repair.

Description and operation

Fuel Charging and Controls

High Pressure Fuel Injection Components

Item

Part

Number

Description

1

—

Fuel rail pressure pressure sensor

2

—

Fuel injection diverter rail

3

—

Fuel injection pump

4

—

High-pressure fuel supply line (fuel injection diverter rail to fuel injection supply

manifold)

5

—

Fuel injection supply manifold

6

—

Pressure control valve (PCV)

7

—

Fuel injector

8

—

High-pressure fuel supply line (fuel injection supply manifold to fuel injector)

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9

—

Volume control valve (VCV)

10

High-pressure fuel supply line (fuel injection pump to fuel injection diverter rail)

Fuel Injection Pump

The fuel injection pump is located at the rear of the engine between the cylinder heads and is driven

by a toothed drive belt attached to a pulley on the left hand exhaust camshaft. The fuel injection

pump is not timed to the engine. The fuel injection pump assembly contains two different types of

pump, a transfer pump and a high pressure pump.

Fuel is supplied to the fuel injection pump by an electric fuel pump in the fuel tank via the fuel filter.

Fuel then passes through the transfer pump to the high pressure pump. The amount of fuel supplied

to the high pressure pump from the transfer pump is determined by the volume control valve (VCV)

which is controlled using a pulse width modulated (PWM) signal from the engine control module

(ECM). The VCV makes it possible to match the high pressure pump delivery to the requirements of

the engine from the low pressure side. This keeps the amount of fuel flowing back to the main supply

line to a minimum and reduces the load on the high pressure pump, improving engine efficiency.

The high pressure pump contains three radial pumping elements, capable of generating a fuel

pressure of up to 1650 Bar (23,200 lb ft), connected together which leads via a pressure control valve

(PCV) to the high pressure outlet of the pump.

The PCV is located between the high pressure and the fuel return line outlet of the pump. The PCV is

controlled using a PWM signal from the ECM, and controls the fuel pressure in the fuel diverter rail

and fuel injection supply manifolds. Opening of the PCV diverts fuel to the fuel return line and back

to the fuel filter. At the same time as the PCV opens to reduce fuel pressure, the ECM closes the VCV

to reduce the amount of fuel delivered to the high pressure pump. When the engine is stopped the

VCV closes and the PCV opens, this relieves the pressure in the system and returns the fuel to the

main fuel supply line.

The PCV and VCV must not be disassembled from fuel injection pump. If either of these components

are found to be faulty, the fuel injection pump must be replaced.

CAUTION: If any of the high pressure fuel pipe retaining nuts are loosened, the high

pressure fuel pipe it is installed to must be renewed. Failure to follow this instruction may allow

metal fragments to enter the fuel system and result in damage to the fuel system components or

engine.

CAUTION: The high pressure fuel line olive end deforms and work hardens during

installation. If any of the high pressure fuel pipe retaining nuts are loosened, the high pressure fuel

pipe it is installed to must be renewed. Failure to follow this instruction may allow the high-

pressure fuel line to leak.

Fuel Injection Supply Manifold

The fuel injection supply manifolds are reservoirs for the pressurized fuel that is produced by the fuel

pump. The two fuel injection supply manifolds are connected by high pressure fuel pipes to a fuel

injection diverter rail mounted on the fuel injection pump. The fuel injection diverter rail also

incorporates a pressure sensor so that the ECM can monitor/adjust the pressure of the fuel to be

injected into the each cylinder. The fuel injection diverter rail and the pressure sensor are serviced as

an assembly and must not under any circumstances be disassembled.

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