Crank (almost) no start
 

Hello all, I have a bit of a strange issue I have been dealing with, I hope someone can help me out or has some ideas. It has happened twice now, where I will try and start the truck (98 gmc sierra, 5.7, automatic) and it will crank and crank and crank and not start. Both times I have (barely) been able to get it to start by playing with the gas pedal while I crank it, maybe it has helped, maybe not at all. The two times it has happened have been after the truck has been sitting for a few days, and over those days, both times we believe the weather has also gotten colder. While cranking, it also smells very heavily of gasoline. And I remember last time this happened, after I got the truck going, I fired it up multiple times that week, before I took it out on the road, and though it would fire up just fine, sometimes, it would again smell like gas.
If anyone has any ideas as to what could be causing this strange issue, let me know.
Thank you.

Leak
 

Possible gas leak between gas tank and fuel delivery system. Run all gas lines looking for leaks. Put cardboard on ground and park on top of it overnight. See if stained next day.
I'm not a mechanic but that's where I would start.