I rented one from AutoZone which is a Schrader connection but it is to big and won't thread to the fuel rail.

 

Is the kit missing any pieces? There are different sizes, but I would think the kit would have them. I bought a fuel pressure gauge from Harbor Freight for $20 a long time ago. It always seemed to have what I need. Or I could always rig something up, if the car had no Schrader valve.