Fuel delivery system - Td5 (Description): Description and operation

Description

General

The fuel delivery system comprises a fuel tank, fuel pump, fuel pressure regulator, five injectors and a fuel filter. The system is controlled by the Engine Control Module (ECM) which energises the fuel pump relay and controls the operation and timing of each injector solenoid.

Unlike other Diesel engines, the Td5 engine has no injection pump. The diesel direct injection system receives fuel at pressure from a two stage fuel pump located in the fuel tank. The system incorporates a fuel return to the fuel pump, via a fuel cooler attached to the inlet manifold and a fuel filter. A fuel pressure regulator is located in a housing on the rear of the cylinder head. The regulator maintains the fuel delivered to the injectors at a constant pressure and returns excess fuel back to the fuel filter and pump via the fuel cooler.

A fuel filter is positioned on the chassis to the right of the fuel tank. The fuel feed and return to and from the engine passes through the filter. The filter also incorporates a water sensor which illuminates a warning lamp in the instrument pack.

A moulded fuel tank is located at the rear underside of the vehicle between the chassis longitudinals. The tank provides the attachment for the fuel pump and fuel gauge sender unit which is located inside the tank.

Fuel tank and breather

The fuel tank and breather system is a major part of the fuel delivery system. The fuel tank and breathers are located at the rear of the vehicle between the chassis longitudinals.

Fuel tank The moulded fuel tank is made from High Molecular Weight (HMW) High Density Polyethylene (HDPE). The diesel tank is manufactured using a proportion of recycled plastic.

The tank is retained in position by a metal cradle which is secured to the chassis with two nut plates and bolts at the rear and a stud plate and two nuts at the front. A strap above the tank is bolted to the chassis and restrains the tank from moving upwards. The fuel tank has useable capacity of approximately 95 litres (25 US Gallons).

An aperture in the top surface of the tank allows for the fitment of the fuel pump and fuel gauge sender unit which is retained with a locking ring.

A reflective metallic covering is attached to the tank with two scrivets to shield the tank from heat generated by the exhaust system.

The fuel filler is located in the right hand rear quarter panel, behind an access flap. The flap is opened electrically using a switch on the fascia which operates a release solenoid.

The filler is closed by a threaded plastic cap which screws into the filler neck. The cap has a ratchet mechanism to prevent overtightening and seals against the filler neck to prevent the escape of fuel vapour. The filler cap has a valve 2

which relieves fuel pressure to atmosphere at approximately 0.12 to 0.13 bar (1.8 to 2.0 lbf.in ) and opens in the 2

opposite direction at approximately 0.04 bar (0.7 lbf.in ) vacuum.

A moulded filler tube, made from HMW HDPE, connects the filler to the tank via a flexible hose. The filler tube is connected at its top end behind the filler flap.