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

The fuel pressure regulator is located in a cast alloy housing which is attached to the rear right hand corner of the cylinder head with three flanged bolts and sealed with a metal gasket. On pre EU3 models there are two ports in the housing that connect with ports in the cylinder head for fuel pressure feed and return. On EU3 models there is a port in the housing that connects with a port in the cylinder head for fuel pressure feed and a single external port for fuel return. A gauze filter is located in the pressure feed port in the cylinder head and filters the fuel before it reaches the injectors. The filter is a fit for life item but can be changed if required. An 'O' ring is located in a recess in the cylinder head and provides additional sealing for the pressure feed port between the gauze filter, the cylinder head and the housing.

A union and pipe is attached to the feed port in the housing and connects with a quick release coupling to the fuel pressure feed pipe from the fuel pump. A second union and hose is located in the return port and provides the fuel return connection to the fuel cooler. A third port provides location for the fuel temperature sensor which is sealed to the housing with a bonded seal. The fuel temperature sensor is used by the Engine Control Module (ECM) for engine management.

The fuel pressure regulator is located in a machined port in the lower part of the housing. The regulator is sealed in the housing with two 'O' rings and secured with an internal circlip. 2

The regulator maintains the fuel pump delivery pressure at 4 bar (58 lbf.in ). When the fuel pressure exceeds 4 bar 2

(58 lbf.in ), the regulator opens and allows fuel to return to the fuel tank via the fuel cooler. The fuel returned from the regulator is directed back into the fuel filter before being drawn by the high pressure stage of the fuel pump and directed back to the injectors. A special tool can be attached to the regulator housing fuel feed port and allows for the fitment of a suitable gauge to measure fuel pump delivery pressure.

Injectors

1 Solenoid housing 2 Electrical connector 3 Push rod socket 4 Push rod return spring 5 Housing 6 Fuel delivery port

7 Fuel return port 8 Nozzle cap nut 9 Copper washer 10 Nozzle 11 'O' ring 12 Cap screw 2 off