'02 Tahoe will not start!

I just parked my truck after a 200 mile trip and now it's a day later and it won't start. It tries to crank over easily and has plenty of juice but it's acting like it has no fuel. My first thought was that the downhill angle that it was parked was causing the low amount of fuel in the tank to not reach the fuel pump pickup but I don't know. Gauge shows about 1/8th of a tank and it's parked facing downhill but it's really not that steep. It has 60K miles and a battery that's only about 6 months old. Any ideas?! It's also been raining over the day that it was parked but I really doubt that has anything to do with it.
TIA

Well I feel dumb. It was the fuel level. The gauge showed 1/8th and it was parked facing downhill slightly but apparently enough to prevent fuel from reaching the pump. I put about 5 gallons in it last night and it started right up.