We ran the genset today with interesting results. There are four fuel tanks on this yacht and they are set up in two banks of two. The two port tanks feed the port aux and genset and the starboard tanks feed the starboard aux. Each tank has a shut off and there is a combiner that connects all four.

Yesterday was nasty so we ran the genset for a bit, made ice, charged batteries in the absence of sun, etceteras. The port bank was low so I opened the combiner but the port and starboard tank levels stayed independent. Hmm, one item to check on.

Today the genset died in the middle of a morning run. Sounded like it was out of fuel. I checked the port fuel bank level and it had more fuel than when we fired the genset up. Hmmm, nothing like a nice puzzle on a rainy day.

This ad hoc experiment inspired an inspection which turned up a kink in the hose between the inside tank and the fitting that leads to the engine bank. There was plenty of fuel in the outside tank though so why the failure?

After a bit of research I determined that the problem was that the return from the diesels comes into the filler hose. The filler hose goes down to the level of the top of the tanks and then hangs a 90 degree turn, running across the tops of the tanks. Of course this means that, when there is room, the inside tank gets all of the return fuel. I'm not sure of the exact ratio but from this experience I would guess that at least as much fuel is returned to the tank as that which is burned in the engine, perhaps twice as much. Given this data you run out of fuel two to three times faster than you should if you don't reuse the returned fuel.

Certainly a condition we are not going to sail off across the south pacific with. What's one more day...