Sorry that your having problems. There have been a few posts that detailed opening up the floor under the bed to access the pump. A last resort! As other posters have asked, did you verify fuel pressure loss with an hour long,engine off , test? When the key is first turned on , before you crank the engine, does the pressure build at all ?
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.