A solinoid is an electrically Actuated componet that can act as a valve, or be used to open or close things. Amoung other uses. On top of you IP, where the fuel line brings fuel into your IP, is a solinoid. It's called L1. It is used to stop the fuel being delivered to your IP. You can call it the fuel cut off solinoid, if you like. It's proper name is L1. That way it's easier and shorter to write, and less confusion.
When I label something here, like L1, S2, S7, and you don't know what the heck I am talking about, look at the Schematics on the doors of your gen set. If the Schmatices are missing, print them out. They are in the -12 manual. You can interchange the 004A and 005A Schmatices. The copys you print out are crappy. So I print out both sets, and look to see what sheet looks best. There are a few mistakes on them, but I will try and warn you about them.
The L1 is held on by 3 screws. Sometimes they have special heads, sometimes not.