turning on the first time on 2005 Chevrolet Avalanche 1500

my truck won't turn on the first time all the'll spin,but won't crank..turn the key back,turn the ignition..truck starts..why is that?

Sounds like you need a new fuel pump. They go sour around 80K/miles. I had the same thing occur except I got 117K/miles out of mine.
I have the same problem with my 2005 but when I had the fuel pump tested it had good and instantaneous pressure. The shop was unable to duplicate the problem at so we replaced the ~75$ relay that controls the fuel pump which did not help. This problem occurs ~30-40% of the time in normal use. Any other suggestions? I have not replaced plugs or wires or cleaned the injectors could this be part of the problem?
2 more answers , 3 more comments
So are you hearing the starter motor spin, but you don't hear the engine turning over? If this is the case, I would check the starter solenoid.
the engine tries to start,but won't...
are you getting a check engine light?

Get'r'Scanned and see if you are getting a P0342 or P0341... Camshaft Position Sensor....
I've got a 2002 z71 avalanche and have a similar problem. My truck works fine and has plenty of power when it wants to. It will not shut down while running but
starts only when it wants to. The engine will turn but I don't have any power to the gauges that normally do. Fuel,voltage,etc.