In may we developed fuel issues which we were told was bad diesel. Got it fixed in May and pulled our 16000 lb rv over the mountains out of Denver to Crawford, Co. 4 months later we get the same issues going and were told its bad diesel. Well we put it in Ford shop and they say they fix it and we fill tank again and 50 miles later fuel pump is singing and I romp down on throttle and it gives the same code. Reduce eng. power and low fuel pressure. Three times now this is happening. Anybody got any ideas whats going on here.

 

Its a 2015

 

Sir, is it possible that the fuel tank is not vented? (thus not allowing air in when fuel is being sucked out) Bad fuel cap or clogged, pinched vent hose?
Eric