Fuel return question

Our new (to us) trawler was recently delivered to our home base in NJ from Fl. It has 2 Perkins 6.354 engines and a generator.

I have noticed that all 3 fuel return lines are closed. I can only assume that it made the trip with them closed. Seems to run fine.

Is this normal to close the return valves? I had always thought they should be open, but I am still a bit of a novice.

Look forward to your comments.
Thanks!

They should ALWAYS be open. If you run them them with the returns closed you'll blow out the injector pumps.

I have seen the results of leaving return line closed. Secondary fuel filter gasket blows out, and lots of fuel sprayed around. This on older CAT engines, don't know about new common rail engines but not a good idea. Older Perkins might be plumbed with return feeding the inlet side,

I would re-trace those lines out again. Something is not right.

High Wire said:

I would re-trace those lines out again. Something is not right.

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Yes. Are you sure they were closed? Are you sure someone didn't close them after the trip?

If you are uncertain, have a diesel mechanic check them. The excess fuel needs to go somewhere.

Some diesel engines return very little fuel. Others return several times what they burn. I know that the Perkins returns a fair amount because on my friend's trawler with twin Perkins 6.354s he uses a cross return to balance the heel that develops.

But in any case there should be a place for the return fuel to go. Are you sure that you are looking at everywhere the return fuel can go? Usually return can be directed to the starboard or port tanks and sometimes forward or aft. As others have said, trace the flow path to find out everywhere it can be going. I'll bet you find another set of valves that are open.

David

Be sure the valves that "appear" closed really are closed. I have seen valves installed incorrectly where the handle appears to be in the closed position but is in fact in the open position. I doubt your boat would run that far without a problem if the valves were closed. The return fuel must be going somewhere.
Congrats on the new boat. Howard

My fuel return goes back to the primary filter - a very simple but effective arrangement, but it works. Of course I only have an old faithful Lehman 120 (non-turbo).

Don't know about your specific engine, but my perkins 4.236 burns around a gallon an hour. But it pumps around 8 an hour. So, either the returns are plumbed back to the primary filter, or you haven't properly traced the lines. OR the valves handles are not indicating correctly.