2000 GMC Jimmy runs fine but sometimes wont start.?

[zero]

2000 GMC Jimmy 4.3 4wd. It will run fine for as long as i am driving,but when i shut it off sometimes it will start,sometimes it wont. I dumped some gas down the throat and it ran long enough to burn threw it.let it sit for anywhere 10-? mins and it starts right up. what are the things that would make it not get gas,I've allready went threw the fuel pump,dist-cap and rotor,fuel filter,and put some sea foam in the tank just incase it was vapor-locking.ANY HELP or SUGGESTIONS is GREATLY APPRETIATED.Thanks

 

[robertguero]

Can you hear fuel pump run or hum when you turn the key to "ON"? Do you mean it will not turn over or will turn over but not start? Have you changed fuel pump relay? There is a bypass wire by battery to make fuel pump run constant. Does the THEFT light come "ON" in the instrument cluster?