Duel Diesel fuel tanks - Link valve on fuel return lines and feed lines

[Fire99]

Hi Guys,

I hope this is the right place to ask but I'm unravelling the mysteries of my new-to-me Trader 47 Sundeck and I've a question about the fuel system with my Twin Caterpillar engines.
I have a large balance pipe between the two fuel tanks which I assume is to enable balancing of fuel levels. This is a relatively large-bore hose.

I also have a valve that links the two fuel feeds. I'm assuming so I can run one or both engines from either tank etc. But I also have valves on the return lines..

Can anyone give a little info on how this works?


Many thanks in advance,

Nick

 

[kashurst]

The return pipe and valves allow you to send the returning fuel from each engine back to either their own tank or both into either port or starboard. Useful if you do not have a balance pipe between tanks. The diesel engines draw about 3 - 4 times more fuel than they actually need so the excess gets sent back to a tank. This also helps to keep the fuel clean as it all goes through the primary filters.
The main balance pipe between tanks is there to level off the diesel so both tanks have the same. Over time they get a bit out of synch and/or if you have a generator that tank will use more. If you are lucky your fuel gauges may actually read the same too, after the balance valve has been open for a while.

 

[Fire99]

Thanks Kashurst. Much appreciated. I did a bit of digging and found that the inlet lines had been set to both tanks would supply both engines (the link between the feeds was open). The return lines had been set to return the fuel to either tank (the link between these two was also open) AND the balance pipe was open...
Oddly the end result was it seems the boat preferred to send the fuel back to the SB tank rather than the Port tank.