If the prefilter oring is bad you will see air in the line that exits the bottom of the prefilter housing. The SOV oring does cause leaks, it will first show in the lil line from SOV to lift pump and all lines beyond that in the fuel flow path. You also have a couple of plastic fuel lines that also rely on oring seals. Theres a couple more on the shaft of your kill switch too.

Air may or may not be the only issue at play. Your best bet is to get it running with no air present and then deal with whatever problems are left.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)