I HAVE A 1996 F-250 WITH A 460 ENGINE. WHEN IT IS HOT OUT, PULLING A 3 HORSE TRAILER AND DRIVE MORE THAN 80 MILES IT ACTS LIKE IT IS RUNNING OUT OF GAS. I CAN SWITCH TANKS AND IT WILL GO A LITTLE FURTHER AND THEN DIE. IT WILL START BACK UP AND RUN FINE AFTER SITTING FOR A COUPLE OF HOURS. I HAVE REPLACED THE FUEL FILTER, FUEL PUMP RELAY SWITCH AND HAD IT INTO FORD TO HAVE THEM CHECK THE FUEL PUMPS AND DO A DIOGNOSTICS. THEY CAN'T TELL ME WHY IT DIES. I WAS CURIOUS IF IT COULD BE THE IGNITION MODULE, BUT HAVE BEEN TOLD THAT IF THAT WHAT IT WAS THEN IT WOULD TURN THE TRUCK OFF WITHOUT SPUTTERING FIRST. ANYONE HAVE ANY SUGGESTIONS?
THANKS!!

 

My first guess would be vapor lock.
If there is an area where the fuel line(s) or rails can get excessively hot, even with a "good" (within specs) fuel pump pressure reading the under-hood temps in some areas of the fuel path can make the fuel boil in the line - hence vapor lock.
The ol' ladys' Taurus would feel like its running out of gas and the cure (well, besides waiting for cooler weather, or maybe shutting off the AC ) was to pull over and dribble cool water around the fuel rail and I believe, it was throttle body(?) that area too. Then git the heck outa traffic and get some air moving underneath. That pump was checked at the low end of the acceptable specs - it just couldn't deal with the heat.
An ignition module that fails is like a switch shutting off the ignition IMO. Fuel pump issues are like "running outa gas".
A backyard fix/guess would be to deal with the areas that look too close to the head, intake etc and maybe try to put a little heat shield in between the heat source and the line. (i.e. aluminum foil, piece of a pop(beer) can?) The less touching to the fuel line the better. Maybe the fuel is picking up heat on the way to the engine too - look underneath?
Good luck. I can picture myself... hot-late-side of the road-p o'ed.