My 1997 international 4700 with the DT466 (not the high pressure oil pump engine) started running rough out of the blue. I was about to leave for the dump when it started missing and after a little while it died. Make a long story short I changed the fuel filter and primed the system back up and it ran good for about 5-10 minutes then I shut it off and parked it. About a week later I went to start it and it ran good but after about 20 minutes it shut off again. After messing around with it I realized that it has lost its prime again! Does this sound like a weak fuel pump or what could be the issue? I park the truck on a concrete pad and do not see any leaking diesel fuel. Any thoughts would be helpful. Thank you in advance!