INTRODUCTION - FUEL TANK AND COMPONENTS

2.4 JTD 20v

FUEL PUMP

Specifications

System details

The fuel pump is part of a single assembly with the level gauge and fuel filter. Components cannot therefore be replaced individually.

Type

The electric pump submerged in the fuel is volumetric roller type with brush motor and permanent magnet excitation.

Operation

Operating principle

Impeller (1) is turned by the electric motor to create volumes (2) that migrate from intake port (3) to outlet port (4).

These volumes are delimited by rollers (5) that adhere to outer race (6) during motor rotation.

The pump is fitted with two valves, a check valve to prevent the fuel circuit emptying (with the pump off); a second pressure relief valve (7) that bypasses the outlet to the intake when pressure levels exceed 5 bars.

INERTIA SWITCH

Specifications

Function

The inertia switch fitted to the left of the driver''s seat cuts off the fuel pump earth connection if the vehicle crashes and thus cuts off the fuel flow to the injection system.

Composition

Operating principles

A steel ball (1) fitted in a tapered housing (2) is normally held in place by the attractive force of an adjacent magnet.

Under specific acceleration loads, the ball is released from the magnetic detent and gradually emerges from the tapered mount. Its upward movement is dependent on cone angle.

A rapid release mechanism (3) over the ball forms a normally closed (NC) electrical circuit.

When struck by the ball, the mechanism changes position from a NC circuit to a normally open (NA) circuit and breaks the fuel pump earth circuit.

The switch may be reset by pressing a button protected by a flexible cover (4).

If a smell of fuel or fuel system leaks are noted after even an apparently slight impact, do not reset the inertia switch but find and repair the fault to prevent the risk of fire. Otherwise, if no leaks are noted and the vehicle can be driven away, press the button to reactivate the pump.