Gas tank access hole

[AST]

https://photos.app.goo.gl/82EDf4rsKuDJejnYA

Hi

I have recently purchased a 1992 sailboat and hence coming to this great group with my questions (thanks in advance)

I need to troubleshoot the fuel gauge (google gave me the needed info). But I want to take out the cap on my gas tank to access/check the float (pls see pic).

I am wondering what should I use to seal it when I want to return the cap on?

And what material should I use to clean the outside surface?

Thanks

[gamayun]

There's going to be a rubber gasket under there that you can either cut yourself or order it from the gauge manufacturer. You might also mark the orientation of the sender. Maybe this is obvious, but it has to go back in the same way.