How does a fuel manifold work?

[callistov42]

I feel really stupid but I am realizing that I'm not sure how my fuel manifold works or is set up. I have two fuel manifolds, supply and return. Each manifold has three valves on top (with hoses to the), port, starboard and forward (tanks). Then there are hoses going into each end of the manifold. Since I have a main engine and a generator, I assume the one fuel line provides fuel for the generator the other fuel line to the engine. The return side works the same way getting fuel from either the main or the generator and depositing it back into the selected fuel tank. Again, would the two lines on the ends of the manifold be from the main and the gen. Does it make sense that if the return valve from the generator was closed that the gen would run for about 4 hours and then die (a very fuel sounding shut down)? I opened the valves at the ends of the return manifold and the gen restarted.
What's really embarrassing about this question is that I have owned the boat for 28 years. DUH.

[bil56]

follow the lines, one by one, from beginning to end, sketch,
and it will get better!

./.

[jordanbigel]

Originally Posted by callistov42

What's really embarrassing about this question is that I have owned the boat for 28 years. DUH.

You're right, that is embarrassing.

Also, it sounds reasonable to me that if the generator return line valve was shut, the generator would run for a while, and then stop because of the back presssure built up in the return line.

Maybe try remove the hose you think is the genset return line, put it in a bucket and start the generator and see if fuel comes out. Bingo. Now you know (assuming you couldn't already know by tracing the hose because sometimes it is really hard to trace a hose).