GN running great!!!! when it finally starts.....replaced gas tank with brand new one due to rust in the old tank, from sitting while the engine was rebuilt. Car was and is running great! However, when you turn the key on, fuel pressure at 20psi, as you hold the key and it tries to start, pressure slowly builds to 40psi and then it fires right up and runs great. This began after changing fuel tank. What to look at???? Where to begin troubleshooting? Fuel pump is obviously pumping....