Starting problem on a 2001 xtreme
 

When trying to start in normal fashion it will not. You have to engage starter for 1 second then off then back on 1 second then off then it will finally start. like its flooded but does not have any smoke out of exhaust. After it starts runs great with no problems. Any help will be greatly appreciated.

When I say engage the starter then off, I mean not turning the key switch completely off..

Sounds like a fuel delivery problem to start with. Do a leak down test at the test port on the fuel line in engine compartment then do the MAX Pump Pressure test at outlet of fuel filter and let us know what the readings are.

It has new pump from GM. When it does start it's when I let off key. Sorta like the ignition switch.

These trucks have a known issue with the ignition switches. I don't know how you test them but maybe some one here does. I do know some people who have had issues like this have replaced the switch and it did clear up their issue so that may help you if it is the switch. probably couldn't hurt but i would still check for codes in any case to be sure.