won't start immediately

Hello, This sounds like vapor lock. When the engine is warmed up and not running, it's important that fuel pressure is retained in the fuel injectors and fuel lines. This prevents the fuel from vaporizing (vapor lock). The fuel pump likes to pump fluid, not vapors, so when this occurs, the fuel pump is unable to deliver the proper amount of fuel to the injectors. What does this all mean? You may have a fuel leak from and injector, or the check valve is bad. Have the residual fuel pressure checked to determine if this is indeed the case.