I understand that they now have fuel at either Baja Naval or Cruiseport Marina. FYI, Cruiseport marina is new, exceptionally clean with an attentive manager and excellent security (they are located adjacent to the cruise ship docks which have a high fence and 24 hour security. I've actually had difficulty getting friends in if they don't remember the name of my boat!) Cruisport is within easy walking distance of town and several reasonably priced hotels/motels, a nice plus
The Mexican petroleum industry (PEMEX) is nationalized. By law, all the fuel at PEMEX stations in Mexico is priced identically. For years, Coral was the only game in town and got around the law by charging "docking fee" that amounted to a 10%+ surcharge if you weren't a guest at the hotel. Since it was often difficult to get a slip or a reservation you had no choice but to pay what amounted to mordida.
Recently, Cruisport or Baja Naval got a fuel dock (I'm not sure which). I'd call to make sure that it was functioning and their hours of operation. With the reduction in the number of smaller boats taking offshore delivery both marinas are far less busy so you have more choices. However, If I were going down and planning to sleep aboard, I'd give Cruisport a call. I think you'll like the facility.