Thanks for all the help.
It's 100% an air in the fuel system problem. The odd thing is I can't seem to prime the fuel system properly.
I unscrew the lid of the primary filter (empty). Fill it with clean diesel
. I unscrew the priming nut, and pump the priming lever until airless diesel comes out. I screw the nut in. I go back to the primary fuel filter (no longer full) top it off with diesel. Go start the engine. It runs great for about 45 seconds then dies. If I unscrew the priming nut and pump the priming lever only air comes out. If I check the primary fuel filter its empty. The boat has plenty of clean diesel in the tanks
. The fuel valve is open.
Not sure what else to do. My plan is:
Buy primary fuel filter replacement.
Buy a filter wrench small enough to unscrew my secondary filter (couldn't unscrew by hand).
Prime the two new filters, prime the fuel pump, maybe prime the injectors.
If that doesn't work I'll bring in a mechanic
and hopefully learn something.