2008 F350 w/ 6.4 diesel. I installed a sliptank and installed it directly into the fuel fill spout. It fills with a 12 v pump, low volume. Inlet and outlet lines are installed so if the tank fills up it will just return back to the tank and not pressure up. Since I have installed it though the fuel gauge hasnt moved down, Couple of days driving 120 miles. I know when I filled the tank it was right full so it was returning back to the sliptank. Would it make that much of a difference to have it that full or do you think the fuel float might be stuck. Thanks.