Engine Stop Solenoids

What is an engine stop solenoid?

The engine stop solenoid is an electromagnetic device that shuts off the fuel supply to the engine when the ignition switch is turned off. They are an essential part of almost all diesel engines. The engine stop solenoid was not energized in its normal state (i.e. no power). In this state, most of the solenoids are in the closed position, which prevented the flow of fuel. Before the engine starts, the solenoid is energized and fuel flows to the engine. The motor crank is then started. When you stop the engine, power to the stop solenoid is removed, the fuel line is cut off, and the engine is stopped. This means that if electrical power to the solenoid valve is lost while the engine is running, the fuel supply will shut off and the engine will shut down.

Where is the engine stop solenoid located?

The engine stop solenoid is usually located at the fuel injection pump inlet or in the fuel line ahead of the fuel injection pump. When stopped, the solenoid will not be powered and will need to be charged to allow the motor to run. In the case of generators, the solenoids are usually controlled by the generator control panel. When you press the start button or turn a key, power is sent to the solenoid valve which opens before the engine starts. If the solenoids are not on, the engine cannot start, because it will not be supplied with fuel.

An idle stop solenoid

Most older cars have a device called an idle stop solenoid that closes the throttle when the key is closed. It prevents the engine from continuing to idle once fuel and air stop flowing to the engine. Fuel injected cars do not have such a device. In the case of fuel injection, fuel is delivered by an electronic pump to the ejector, which is electronically ignited so that when the key is closed, there is no fuel transfer.

Signs of a bad idle stop solenoid

1. Engine idling too high.

2. The engine crackles or shakes for a while after the key is turned off.

3. Significantly worse fuel economy.

If your idle stop solenoid fails and you experience engine running, it can be harmful to your engine as it interferes with the normal "cool down" phase and your fuel economy will also drop. If your idle stop solenoid is considered faulty, replace it as soon as possible and also keep it in mind that faulty idle stop solenoids check is not part of routine maintenance.