Engine Operation 28 UENR0623-02 The fuel pump assembly consists of a low-pressure transfer pump and a high-pressure fuel injection pump. The pump assembly is driven from a gear in the front timing case at one a half times the engine speed. The fuel injection pump (1) has one plunger that are driven by a camshaft. The stroke of the plunger is fixed but the volume of fuel that is provided by the fuel injection pump is controlled by the suction control valve. The injector will use only part of the fuel that is delivered by each stroke of the pistons in the pump. The suction control valve (2) for the fuel injection pump is controlled by the ECM.
This maintains the fuel pressure in the fuel manifold (rail) at the correct level. A feature of the fuel injection pump allows fuel to return to the tank continuously. The fuel injection pump has the following operation: Generation of high-pressure fuel The fuel output of the fuel injection pump is controlled by the ECM in response to changes in the demand of fuel pressure. Shutoff The engine shuts off by preventing the electronic unit injectors from injecting. The ECM then closes the suction control valve to prevent the pressure in the fuel manifold (rail) from increasing.