I need new copper crush washers to install my fuel rails, but The only size I can find have a larger outside diameter than the OEM ones. I just wanted to know since it's a 12mm if it would work or not?

 

here is a picture of the two washers, do you think the bigger one will work?

 

Should be OK as long as the outside isn't so big it's hitting something and preventing a seal. The ID has to be dead-on, though.

As always when working with the system, make SURE to pressure test the system after installation and carefully check for leaks.

Dale