I know when I installed my Fass I used the supplied line from the kit for the feed to the pump then U used the original feed line as the return since it was larger ..............just a thought

 

When I put my FASS on I had a buddy help. We used the FASS supplied line and he fitted it on the tank which is why I didn't know how to do it.

After your help yesterday I went out to the truck and managed to get a look at the tank fittings. He had used 2 hose clamps on the FASS supply line just as you suggested. I got the return off and now have a new return line fitted also with 2 hose clamps. The origional line is nylon cored so there is no way to use regular fittings on it, plus is is only 1/4 inch i.d. I needed to have the line from the tank go to one port of a solenoid valve (DR) and the return line from the engine/IP (R) go to another port both of which have 3/8 fittings which is why I'm using 3/8 line. The other port (VOR) loops the Veg Oil back to the suction side of a second FASS pump.

Yoy are right, it IS fun