Does anyone know where the fuel pressure check valve is? Is it in the pump or in the regulator? My manual says to check it but doesn't really say where it is for sure. I suspect its bad because with a gauge connected to the fuel rail, sometimes it holds pressure, sometimes it doesn't. I can't find any pattern to it. Should the rail hold pressure after the engine is shut down? Mine doesn't, drops to about 10 psi. Then sometimes when I turn the key back to "on" it'll pressure up and hold, other times it will pressure up then drop back to 5-10 psi...
