Thanks all for your suggestions, I will replace the hose and use proper clamps.
It was a Cummins Power Generation Product Support Bulletin: CPGF-S-00000198-0
Fuel Filter Replacement Procedure for models HGJAB, HGJAC, HGJAE, HGJAF
They changed both fuel filters to new part numbers. The lower one at the pump is replaced by filter 0149-2341-01. The upper one by the carb is replaced not with a filter but with a simple adapter fitting A029S253.
All I am doing is replacing the one by the carb with A029S253. My Cummins service center in Charlotte had it for $19. The lower filter by the pump was the same one that was leaking at the carb (0149-2629) but mine is not leaking there as far as I can tell and it appeared to be harder to work on.
