I'v got a F550 when we were building it we put a 70 gallon tank on top of the bed. To feed it to the factory aft axle tank I ran a hose from the top tank to the factory one. On top of the factory tank was a fitting that appeared to be for exactly my need (filling the tank) it didn't have a tube so I knew it wasn't to supply a generator or anything. So that is how I plumbed the tank. It worked, well sorta, on a long trip the truck burns it faster than it feeds back in. In the hotter weather it would often not feed at all. In the heat when you would open the factory cap air would hiss out. I recently installed a pump with the hopes it would help.
. I have not had it long enough to see how it works but it is SLOW! and with it even in this cold air hisses out when the factory cap is removed.
The fitting I tied in to is the one on the right that kinda looks like a crop circle.
So my questions...
1 Is the fitting I used on the factory tank made for what I used it for?
2 Is this pump okay for my purpose?
3 What is the air hissing out of the tank? I believe the cap is supposed to vent, is it not venting?
4 Any suggestions?