Hi Rick. It indicates fuel pressure to the injectors. Ron Haskell rdhaskell at juno.com Riverside, California USA http://albums.photo.epson.com/j/AlbumList?u=3009370&f=0 On Sun, 5 Mar 2006 20:28:51 -0500 "Rick Rowlands" <jrrowlands at neo.rr.com> writes: > What is the large gauge for? It goes up to 5000. > > Rick