Electric pump on an 8.3L is peculiar to begin with. What is the "awesome pressure" of the fuel during a hot no-restart situation as measured after your engine mounted fuel filter and before the injection pump? Diesel fuel gets very warm and almost hot during use since it is recirculated. I would first suspect your electric boost pump to not be high temp rated and is the cause, or the overflow valve in your injection pump is hanging open. People will often Band-Aid problems without finding or resolving them correctly. If the OFV (over-flow-valve) is stuck open, it will starve for fuel, and somebody may thing it is a fuel pump issue and put an electric pump on it. I'd get it back to stock configuration and check injection pump inlet pressures to begin with, especially during a no-start condition. The OFV can be cleaned very easily by pinching closed the return fuel line at the front of the pump for 10-30 seconds at an idle and release it. This is also a good test to see if the OFV is the issue. If the truck will not start, pinch the retun line shut with Vice-Grips, and then try to start the truck. If it starts, the OFV needs to be cleaned or replaced. This is built within the banjo bolt fitting on the injection pump return line. Very easy to get to and do.
