I have a 1980 Jeep CJ7 with a 4.3 Vortec out of a 2001 S10. It has an inline EFI fuel pump.  While it is running, It tests at 54 PSI. After I drive it for an hour or so in hot conditions, it doesn't really bog down, it just completely stalls. It acts like it is getting no gas at all. After a few minutes it will start back up and run for a few more minutes before dying again.  I changed the ignition module and fuel filter.  I tried putting on a Holly fuel pump and it wouldn't even try to start. I've noticed that when I drive it at night and it is cooler out, it seems to run fine.  My inline fuel pump is located in the rear of the jeep, and the fuel lines do kinda run close to the exhaust.  Do you think moving the fuel lines or shielding them will help? Will it do this if the crankshaft sensor is going bad? Can I test the fuel pump for correct pressure with the engine not starting?  

From my experience on these Vortec fuel systems your pressure is fine. It sounds to me like your fuel lines are getting hot, causing a vapor lock problem. Sheilding them might help but if you have room to move those lines thats what I would do. On these systems you should see from 50 to 55 psi key on enjine off, or at least cranking.  

Any luck with your problem? I have the same problem with my 86 CJ7 with a 4.3 vortex.