Fuel Shut-off Solenoid: Description and Operation

Fig. 30 Fuel shut-off solenoid:

Since diesels do not use spark ignition systems, the engine is switched off by a fuel shut-off solenoid on the injection pump.
Current is supplied to the fuel shut-off solenoid whenever the ignition key is on. The magnetic coil pulls the solenoid plunger up against the spring, opening the injection port for injection, Fig. 30.
Whenever the ignition key is turned off, the solenoid closes the intake port, cutting off the supply of fuel for injection from the vane pump.
The engine will not run if the fuel shut-off solenoid sticks closed. If it sticks open, the engine will continue to run after the ignition key is turned off.