Can't keep fuel equal in tanks.

[DVT873]

The return line should NOT be going into a standpipe. On either side. If one is and one isn't that is likely the problem. The FASS return needs split also.

Only other thing is the line pairs need to the same height. So both returns have to be as close to the same height as possible. If one return is close to the floor of the cab and the other one is on the top of the frame making them say, 6 inches apart in height, there will be a problem. Same for the draws.