Also as I try and start truck it pours white smoke from exhaust. Any thoughts would be welcomed

 

White smoke is always indicative of Water or coolant in your exhaust system. Check your coolant level and note its level Cold and then Hot. Check the level the same time everyday to see if it has become lower. Now thats WHITE - if its bluish then its oil in the exhaust indicative of bad rings/valve guides and even bad PCV.
On the white smoke - it could be a bad head gasket or as simple as a intake coolant leak into one of the intake ports. Investigate the coolant levels first. You could when cold - fill the coolant to the approx level on the container precisely and then monitor it when its cold andf hot. Make sure it is NOT low by any means.

 

White exhaust is usually coolant. What year made of truck and engine? There's a few ways things can leak, usually head gasket, where you can get coolant mixing with air/exhaust and or oil so I'd check the oil to see if its .. well oil or a milk shake looking concoction. Check coolant levels as Dion stated, and compression check the cylinders looking for the problem.

You can also get a tester to check for exhaust gases in the coolant system, but that only checks for one specific type of leak.

If it's a 96-01 or so with the GM cast 506 turbo block it could be the #8 cylinder crack.

Another test is to check for coolant in blowby, if you have the truck running, take the oil fill plug out and see if white puffs of smoke come out from the fill port.

 

If the engine is runing and it steadly smokes white that is not good and you are burning coolant. If it smokes a little bit under load (while driving) black , this is ok. If the smoke is blue then it is burning oil and this is also bad. If the engine wont run and you are cranking over the engine to start and it smokes white that is normal and the engine is getting some fuel. Is the engine cranking slowly or normal speed? Is the coolant low or buttery looking? Is the oil over full, low or looks like butter? I would need some more info to help. Give me a call i would be happy to help.

 

Thx for comments ... it was only when it was trying over when it wouldn't start . I eventuality for it to start and it runs great . What what have caused it to be so difficult to start after not starting it fot only 5 days?
would you happened to know a good H1 shop in Atlanta ?

 

The hard / slow starting issue could be that the fuel lift pump is not working. Do you hear anything when you turn the key-faint buzzing or clicking coming from the pump that is mounted on the fire wall on the driver dide in the engine bay? It could also be a pin hole in a fuel line causing it to suck air and loose fuel prime.
I dont know anyone near alanta. I might be the clocest hummer shop to you and im near austin or you could send it to Big Dog Offroad in golden co. We have clients ship there hummers from all over the country.