My dad has a 98 s10 pickup with a 4.3l v6 he's been having this problem for a couple weeks and I have no idea what is wrong with it. The truck will start up just fine when cold but if you let it idle for 10 minutes then turn the engine off and try to start it again it cranks but won't start but if you let it sit for another 10 minutes it will start up just fine as if nothing ever happened. A few weeks ago I changed the fuel filter and it seemed to fix the problem for about 2 weeks then the truck sputtered and died on him in traffic and has been having this problem again. I'm almost wondering if vapor lock is occuring since we live in phoenix and its starting to get over 100 if you guys have any ideas I would greatly appreciate it cause its his only vehicle and I don't have the money to take it to a mechanic because my truck has a blown head gasket that I'm fixing.

 

so totally sounds like vapor lock to me...First, check the fuel lines and try to shield them from the exhaust. Also check your fan. One reason why manufacturers installed electric fans way back when was to keep the engine cool as the temps rose, regardless if the engine was on or not. You know the stickers: "keep you hands away from blades cause fan can start at any time blah blah...". So check that your fan is operating as it should. I have heard of some people re-routing their fuel lines to get them further away from the exhaust etc.