Maxxforce 13 getting fuel in oil

On a 2010 transtar with maxxforce 13 I noticed today it was an inch overfull on dipstick when the last time I checked it was low. I called international dealer and they said injector o ring but it seems to me more like fuel pump since I just ran it an hour and checked it and now it's 2 inches over so it's getting fuel in oil while it's running so I would think if it was injector it would burn it so seems more like pump especially since about a gallon running an hour. I did recently have all the injectors rebuilt. I barely use the semi so it mostly just sits. Is it possible for it to be pump and how hard to fix? Also it sat for almost a month and yesterday it took alot of cranking and pumping primer to get to it start.