I am looking for a schrader valve adapter and not having much luck finding one. What I am looking for is a small adapter that one end will thread onto the schrader valve on a fuel rail and the other end be female 1/8npt threads. I have found a couple on google, but they require you remove the valve core and then wrap the threads with tape to make it seal. What I am wanting to find is one that will depress the valve core and also self seal (with a o-ring or something) just like a regular aftermarket fuel injection pressure test gauge.
This would not be for a permanent install, so that's why I am wanting one that will self seal and depress the valve core.

Does anyone know if there is such a thing? I figured if anyone would know, someone here would.
Thanks.