These newer common rail fuel systems have a lot finer filters. When it starts bogging down like that change the small filter. That is the 3 micron filter. The other is a 10 micron filter. Ours last anywhere from 100-200 hours in combine service. The filters come with a speciall funnel for filling them with diesel. Be sure you fill the filter all the way to the top before installing. Otherwise you have to bleed the lines and that's no fun.