Weird No Start/No Fuel Pressure condition on hill

[Rob88]

I was parked on a hill outside my house last night. maybe a 20% grade, nothing crazy. This morning, the truck started, and almost immediately died. It would not restart, only crank. I did not have a fuel pressure gauge at this time, but there was no fuel coming from the valve on the fuel rail when I pushed it in.

I used starting fluid to start it and move it to flat ground. Once on flat ground it ran fine again. I got a fuel pressure gauge and it reads 54lbs static and about 48lbs at idle. I was thinking maybe the hill caused some sort of vapor lock condition, or the fuel filter is extremely clogged causing a restriction. Both of those scenarios seem unlikely though. Any ideas?

 

[retiredsparky]

Fuel level in tank?

 

[Rob88]

Tank is almost full. it repeated the no start condition today on level ground. about 6 hours later it started without issue. The temperature the last 2 nights has gotten down into the low 30's. I'm wondering if this isn't coming into play some how.