There is a coil same as generator inside the flameout solenoid valve that generate magnetic force pulling off switch back to oil when is energized, but there is no magnetic force when is out of electricity. Through spring, push it to the extinction, then no oil is supplied. After long-term use, the piston of flameout solenoid valve is easily blocked by dust and dirt and unable to move, which in turn causing unable to start or quench. It need unload and clean, and cannot be coated with lubricating oil inside, because the solenoid valve is next to the engine, and lubricating oil easy to be mixed with dust and dry to mud by engine high temperature. When such a problem comes out, you can pull, fix or unload to line pull, or, you can clean or replace it.