My FW fill connection and vent are located close together. Although seperate (the vent is a smaller area to the side of the fill area with a tiny screen in it). Sometimes during a fill of the FW tank (depending on the water pressure) I would have a problem. Water comming out both the vent and the fill. My cousin told me to make a filling rig (trickle effect) and keep it in a ziplock bag. It has a shut off valve in it that I partially closed and removed the lever after a proper flow (and it works great). Yea, it takes a couple of minutes longer to fill. Now when water starts to "Leak" out of the fill connection it doesn't come out the vent nor does it gush out the fill.
Don & Dona W/yorkies Gizmo, Master Chief, & Tali
2011 Flagstaff 8528 BHSS 2015 Ford 6.7 XLT
2010 Full Timers & Still Going