We have a 1986 Catalina 36 with a Universel M25, 21 HP Diesel engine. We went out for a sail and as luck would have it the wind did not come up. So after sitting there with our sails up for over an hour we decided to go back to port. We started our enging, and started for home when the engine started to slow down, not react to thottle, and sputters to a stop after only running a minute or so. Trying to restart, it would start, and then sputter to a stop. I changed fuel filters (did not bleed anything) and turned on the eletric fuel pump until it slowed to its normal click, click, click. I tried to restart and it would restart and sputter to a stop, soon it would only fire, acting like it would start, but never quite starting, after multile atempts, I gave up as the wind came up and I sailed back to port. I do have a Racor water seportaor filter, before the stock engine fuel filter. It has a new fuel tank from Catalina and I have run about 20 galones of fuel through it. Since it died slowly and it did restart, I feel the engine may be OK, but that I may have a fuel problem. Any idea? Thanks Bob C-36