I have had problems with some engines with the fuel shutoff solenoid. When the electricity is shut off, the spring tension pushes the plunger to shut off the fuel flow. When the ignition is on, the electromagnet is supposed to hold the plunger back letting fuel flow. Sometimes these fuel solenoids have intermittent problems particularly when the system voltage peaks and the engine is hot during a long run time. In one particular design I have had rusty looking silt buildup in the plunger cavity not letting the plunger retract fully and causing reduced fuel flow at high power demand. I have known of some that have cut the plunger off and reinstalling the solenoid with or without the electrical connector plugged in. I also know of some who have removed the solenoid and installed a plug of the correct threads in it's place. I know that these solenoids cost around $100 to replace.
The problem with governed small engines is that when the engine is shut off, the governor will sense the falling RPM and increase the throttle in an attempt to maintain the RPM selected by the throttle lever position. This puts raw fuel into the engine, some of which ends up in a hot muffler and a loud bang from flashing fuel sometimes results. This is one of the reasons for the fuel shutoff solenoid, the other being an emissions issue. Run on of a hot engine as this fuel passes thru sometimes does happen even with a correctly functioning shutoff solenoid.
Mad Mackie in CT:biggrin::laughing:
