Fuel system - Design and function
Fuel shut-off valve supplied with voltage during stopping General Fuel shut-off valve for stopping the engine. The valve changes the direction of flow in the fuel system during the stop procedure. A. Solenoid valve B. Valve housing
Connections in valve housing, markings: T. Inlet from fuel tank F. Outlet to feed pump P. Inlet from fuel filter
0 Volt
I.
The diagram shows the fuel flow during operation.
Outlet to injection pump
Tightening torque for pipe connections: 22 Nm.
Function During operation
During the stop procedure
The valve is not connected and the fuel has the normal direction of flow. The fuel pump (3) induces fuel from the tank (5) via the pre-filter (1) after which the fuel is pressed through the fine filters (4) and on to the injection pump (7).
When the key switch is moved to the stop position (“S”) the solenoid valve (2) is activated. The valve therefore changes the direction of the fuel flow to and from the feed pump, whereby an underpressure of 0.3– 0.4 bar is built up in the injection pump’s fuel chamber. This prevents filling of the pump element and the engine stops (the pump element requires overpressure for filling). The overflow valve (6) prevents fuel flowing into the injection pump via the return pipe.
0 Volt
12/24 Volt
Flow diagram, fuel shut-off valve Engine in operation (the solenoid valve is not activated)
Flow diagram, fuel shut-off valve The stop function is activated (the solenoid valve is connected)
78
