Hello everyone

I have a 1988 camper it's on a Ford F350 chasse with a 460 ci. engine. Has one gas tank with a low pressure pump in it and a high pressure pump on the frame rail. The truck runs for an hour and dies. at that point there is no fuel pressure or spark and the high pressure pump is hot. I replaced the high pressure pump and the fuel pump relay but it didn't help. Can anyone tell me why the high pressure pump could be getting hot and would it cause it to not have spark ?
driving me crazy

Thanks,
Dana