I have a 2007 Trailblazer 4.2L (6 Cylinder) that's slow to start (extended crank). I replaced the fuel pump about a year ago. When I turn the key to the "On" position I can hear the pump run for a couple seconds and then stop. However, I'm getting no pressure reading when I connect a fuel pressure gauge to the fuel line with the key on but the engine off. After the engine starts up the fuel pressure goes up above 50 and holds. When I shut the engine off the pressure then drops quickly back to zero. Is the fuel pump bad again or could there be anything else to check that might be causing the fuel pressure issue?