Just found a fuel / air leak. My truck was starting to lose fuel prime overnight, and it was getting progressively worse. Picked up a new filter, some hose, and washers for the banjo fittings. Pulled the lines from the filter housing, pulled the housing and changed the filter. Also changed the 90 degree hose from the fuel heater to lift pump. Cleaned the screen under the fuel heater, then removed the heater element and re assembled with new o rings. Beautiful, done, holds prime, starts well, BUT....
The line from the overflow valve to the return developed a crack at the forward most support bracket and was spraying fuel between the block and IP. I have been trying to find an occasional fuel drip, I suspect this was it. Changing the overflow valve might have done it in. Anyway, it seem that there's no way to remove the line in one piece w/out pulling the IP, so I cut it into pieces to get it out. Flared the line about 6" after the overflow valve, and put it back together w 5/16 hose. All seems to be good now. I bought the new line, $68 EEK!, and will put it in when I pull my pump next month. Just putting this on the forum for the next guy searching for a leak..

 

When I had to deal with the exact same problem I bought a banjo with a barbed outlet from the hydraulic shop and replaced the metal return line with hose.
Working great several hundred thousand miles later.

The new dealer replacement line is improved from what I understand.

 

Went the same route on mine. Replaced with fuel line and been great for years.