well a while back i was having a issue with my yukon not starting when it got below a half tank sometimes. usualy when it gets to about a 1/3 of a tank left is when it starts having issues. it did it saturday morning when i got off from working a 16hr shift and i had to call my mom which lives right up from my work and i put 1gal of gas in from her mower gas can and coasted around the lot and it fired right up. i went and filled up at the station next door and it still had 9gals left in the tank! (31gal tank size) it never used to do this crap when i fist got it a little over two years ago but it seems in the past year its been giving me problems. once i swap out the heads on my silverado im gona dd it for awhile and drop the tank on my yukon and check the tank out and see whats goin on. anyone have any input?