Diesel Fuel Supply System — Basic Design (Focus Turnier 1)

Unlike petrol engines, diesel injection systems operate under high pressure. This makes injection pumps, including the peripheral units that regulate the process, very different from their petrol engine counterparts. Engineers distinguish between in-line injection pumps, single-plunger distributor injection pumps, common rail injection systems and pump/nozzle injection systems in diesel engines. Under the hood of the Focus Diesel, a single-plunger distributor injection pump (Bosch VP-30) delivers fuel via delivery pipes and nozzles directly into the combustion chambers. The injection pump is driven by a chain from the crankshaft. On the top side of the pump is the electronic pump control unit (PCU). It uses information from the steering angle sensor and the transmission control unit (PCM) and takes signals from there to control the high-pressure solenoid valve and adjust the start of fuel delivery.

Fuel is supplied to the five-hole injectors via equal-length delivery pipes. The injectors are secured to the cylinder head with clamping screws.

Copper sealing washers protect their upper part from direct contact with the cylinder head. Always replace the sealing washers after each removal of the injectors. The Focus has relatively thin injectors (pin injectors). The injection direction of the five holes of the injector is "aimed" almost at the center of the recess of the specially profiled piston inside the cylinders.