i have a 1996 gmc subruban. the problem that im having is that i thought that a bad fuel put in so i let it run to the end. The truck would start then about 30 to 40 seconds later it would stall on me. Then i whould start it up after a few times then would run great until i turned it off. Then i would have to do all over again. I replace the fuel filter. what else can it be

 

I had a problem similar too yours.. it was a pin hole in the sending unit line just where it comes out off the tank, it would lose it's fuel after it was sitting for a while and wouldn't start.

 

is that easy to see the leak

 

It was going on for a long time before i found the problem, I tried everything with that.. till one day i noticed the top off the tank was damp from the fuel. I had too take out the tank, and got the sending unit rebuilt. Just crawl under there and look up by the filler hose and you should see if it's damp on top off the tank.