Getting injector repairs right with DENSO
Two types of electronically controlled fuel injection pumps offer a completely different injection method from conventional fuel injection pumps.
Distributor (rotary) fuel injection pump
The electronic control system of the distributor type pump consists of various sensors, an ECU (electronic control unit) and an actuator. The sensors detect the running condition of the engine and send signals to the ECU. The actuator controls both the injection quantity and timing according to the signal it receives from the ECU, which calculates the optimum levels for the current running condition of the engine.
Common rail fuel injection pump (supply pump)
The common rail type pump has been developed to meet strict exhaust gas regulations in the 21st century. This system consists of a supply pump, common rail, electronically controlled injectors, various sensors to detect the running condition of the engine and a computer (ECU) to control these devices. The supply pump is driven by the enine and produces high-pressure fuel. An injector is mounted on each cylinder of the engine and the high-pressure fuel from the supply pump is distributed to each injector by the common rail
Mechanically controlled injection pumps are divided into two categories:
In-line fuel injection pump
The in-line fuel injection pump has the same number of fuel pressure mechanisms (elements) as engine cylinders. This type of pump, including the governor, timer and feed pump on the pump's body, is mainly used for medium and large trucks and construction machinery. The pump body is equipped with fuel pressure/feed mechanisms and injection quantity control mechanisms driven by a camshaft. The elements in the pump body feed fuel to each engine cylinder according to the injection order.
Distributor injection pump
The distributor injection pump has only one fuel pressure mechanism, irrespective of the number of engine cylinders. Instead, it has a distributor designed to distribute the pressurized fuel to each cylinder according to the injection order. All the components, including the governor, timer and feed pump, are built into the pump housing. The small, light pump can operate at high speeds – making it ideal for small engines.