I have a starting issue on my 2007 trailblazer SS LS2 engine. Once the car is running everything is good. No rough idle. Engine runs smooth. I turn the engine off and wait 5 min ( or 2hr). Then try to restart and it takes 5-6 cranks to start. I attached a fuel presser meter to the fuel rail. The fuel pressure is 55 to 60 psi. Turn the engine off the fuel pressure goes to zero. Should the pressure stay up when the engine is off? Do you think it is a fuel pressure regulator issue?