Switching fuel tanks

[Thesaltyrudder]

Hi all,

Just got my trawler, been running it up to Boston from CT, looks like only one tank has been draining and when I look at the fuel transfer cables there are 4 hoses and valves. 2 of which come from the top of the fuel tanks, one goes to a fuel water seperator and the other to the old generator.

If anyone has had an old 1982 mainship and is familiar I would like to know how to switcjlh over tanks since the last guy I bought it from can't remember ?...

The valve on the right side has an arrow pointing into the filter, the other is pointing to the hose. My question is am I able to drain from both. And which direction is open? The right valve turns only 90 degrees and the left will turn 180. I'll post a picture, and these two lines run to the top of each fuel tank, thanks much!

 

[jleonard]

The old Mainships always had the fuel return line going into to the port tank.
So if you draw from both tanks, the port will fill up. There was not a "leveling line" between the two tanks.
I used to run the part tank for 2 times longer (approximately) than the starboard to keep them sort of even. (assuming the original Perkins diesel).
Normally those valves would be open as they are shown, and closed when they are turned 90 degrees.
The draw tubes go into the top of the tanks.
Does that answer your questions?

 

[Thesaltyrudder]

Sort of... So it is the original Perkins diesel, nothing was labeled on the panel as to Pitt and starboard, I'll know when I fill up today when I flip the panel switch which side is empty vs full...

So your saying in this configuration of the picture, both tanks are being drawn from?

Since the left valve spins 180 degrees in wondering if it closed right now and needs to have the pointers facing the filter. I'm just worried about changing it and running the engine dry during the middle of my trip.

Thanks, your input is clutch today!

 

[jleonard]

So your saying in this configuration of the picture, both tanks are being drawn from?

I'd have to say yes both are being drawn from.
It would be very easy to verify this by removing the copper tubing going to each valve. If you can push a small screwdriver or a zip tie past the valve it's open. Then cycle the valve and check again to verify that it closes.
That would also let you know what happens when the one valve goes 180.
(I'd probably do that cause I'm a little anal at times)

EDIT: Oh and heed the warning placard on the left of this filter and lubricate that bearing. One or two pumps each season will suffice. They can be a real Bitc(h) to change

 

[psneeld]

Those I believe are only on/off valves. They should only turn 90 degrees so the one that does a 180 may be broken or it's a different model that can go 180, but still only is on/off.

Parallel to the line is on, perpendicular is off.

One way to check would be take them off and check....or as Jay suggests above.

 

[Thesaltyrudder]

Thanks all, little update

looks like I'm draining only from the right tank which is the line that goes 180 (left side on the picture) and the boat will list too the heavy side(port).

So, starboard tank is draining, port tank isn't, however port tank valve only goes 90 degrees. I just don't want to run her dry as she's a diesel. Options? Might have a mechanic look at it so I don't get stuck in Plymouth MA... Although it could be worse places!

Thanks for helping a new guy out

 

[KnotYet]

The valve that rotates only 90 degrees tells you how both should operate but it's
not that unusual for a valve like that to get tweaked by a heavy-handed operator.

Since your boat may have been set up to only return bypass fuel to the port tank,
it is safest to run only on that one tank - at least until you can verify that is true.
Diesel engines can bypass a surprising amount of fuel, often much more than they
burn, which can lead to a tank overflowing if the valves are left in the wrong position.
If your boat does only return to the port tank then use that tank as the primary and
only switch to the starboard when it has been mostly used up.

 

[jleonard]

Those boats return fuel to the port tank that’s why it lists to port.
Like I said earlier the only way to manage that is to switch tank feeds from time to time.

 

[Solly]

Make sure the left valve stem isn't stripped and that the valve is actually turning. Remove the handle and gently try a pair of pliers, channel locks or vise grips on the stem. Actually verify both are working.

 

[boatpoker]

Those boats return fuel to the port tank that’s why it lists to port.
Like I said earlier the only way to manage that is to switch tank feeds from time to time.

or T the return line and lead one end to a newly installed fitting on the starboard tank. Did that today as I've removed one tank and waiting for a new one.

Used ss fitting, drilled and tapped the steel tank ... used Tef-Gel

 

[KnotYet]

or T the return line and lead one end to a newly installed fitting on the starboard tank. Did that today as I've removed one tank and waiting for a new one.

Used ss fitting, drilled and tapped the steel tank ... used Tef-Gel

And install shutoff valves to select which tank the return goes into.

 

[markpierce]

Have two manifolds for fuel: one from source of four tanks, one for return, with four valves per each manifold. Switch as needed to maintain boat level (usually observed while approaching the boat from dock). Without special need, will return fuel to the originating tank.

 

[C lectric]

And never shut off a return line untill the other is opened. Only close the one after the other is opened.

If you dead head a return line it can cause serious damage to the injection pump.