I am going to change the fuel filter this weekend on my car and replace a faulty injector. Is it necessary to have a fuel pressure gauge with relief valve to release the pressure or can I just put a rag or hose over the schrader valve and release the pressure that way? I'm just not sure how much fuel will come out and I don't want to get an unleaded bath.

There should be a one way clip (flow wise that is) on the intake side, *if you have the appropriate tool* you can release that clip without getting sprayed.

Also, you probably have an inertia switch that thows in case of a collision. Find it and make it trip so if you do open a line it's not gong to keep spraying.

Yea, the rag will do. Watch your eyes.

Wear glasses and gloves. Push the Schrader slowly. There's about 45psi in there, and you'll get around two ounces out. What brand car? Most Ford and GM will need a spring connector tool to remove fuel fittings. Almost impossible to release without that.

I can lend you a set of spring clip tools if you need them.