What is this?

I own a 92 Cutlass Supreme S (3.1 L), and my chilton's manual states to "connect fuel pressure valve J 34730-1 to the fuel pressure relief connection." What on earth is J 34730-1? :sly:

Just for elaboration, I have to relieve the fuel system pressure (obviously), and wondered if the method listed above of attaching whatever that thing is to to the fuel rail is absolutely necessary in comparison to doing it the old fashioned way; removing the fuel pump relay/ connector.

The check valve can hold pressure quite a while on some systems. The tool must do it safely but you'd think that overnight would let the pressure relieve.

The 'J' number is the Kent-Moore tool identifier. I've always just used a small screwdriver and a shop-rag to relieve the fuel system pressure. Be sure to wear safety glasses and hold the rag over the port to absorb the fuel as it comes out of the valve. Push down on the schrader valve with the screwdriver. Just be sure to put the screw-on cover back on when you're done.