How to switch fuel tanks on GB36

[GrandWood]

Hoping someone might be able to instruct me on which valves need to be on so that I can run my port engine off the starboard and middle tanks.

Currently the starboard engine is toast and won’t be able to get it swapped out till Oct, already have rebuilt replacement.

Would like to burn up the fuel in the starboard tank and middle tank.

On the fuel manifold in the pic, believe it’s original GB, the starboard valve is on the right, second down, and the port on the left. Not sure what the valves on top are doing for me. Any help would be much appreciated

Thanks
Joe

 

[SIBERNUT]

Not being a GB guru, I would guess the upper valves are the return lines. Appears you can draw from either tank & return to either.
What I find interesting is the different knobs so you know what you're doing in the dark.
Cool! Like the Navy way

 

[GrandWood]

Thank you Sir, much appreciated. Just have to figure out what needs to be on and off, or even drawing from both works

 

[SIBERNUT]

Thank you Sir, much appreciated. Just have to figure out what needs to be on and off, or even drawing from both works

Careful. I was drawing from both and cutting it close on fuel aboard once. Found out one dip tube was 2" shorter than the other......

 

[mvweebles]

I'm not a GB specialist but I don't think it makes a difference.

Top valves are indeed returns. They are labeled as such - see zoomed in of OP picture attached.

What's not clear to me do the round valve handles feed the engine(s) or do they come from the tanks? Another zoom seems to suggest the former. Another mystery to me in the bleachers is how does a third (middle) tank integrate into this menagerie? Three tanks, two engines, supply & return lines for each engine (plus perhaps a generator) makes for a complicated valve farm - a true manifold greatly reduced the complexity, but that's a different discussion.

Sounds easier than it might be, but you need to physically trace the lines and make a diagram.

As a suggestion, if your port tank isn't too full, consider directing return to it to more quickly drain the starboard tank. Caution, entirely possible to over fill a tank this way so you really need to pay attention to avoid a fuel spill.

Peter

 

[SIBERNUT]

Well, you could start an engine & shut off the suspected draw valve. See if it stops. Added benefit , you learn how to bleed the system........

 

[GrandWood]

Well, you could start an engine & shut off the suspected draw valve. See if it stops. Added benefit , you learn how to bleed the system........

Well I learned how to bleed the system when I ran out of fuel on the port tank last week, site glass valve was closed, and well I’m a nub to boating and was thinking that I was getting awesome fuel economy, DOH!!! Thought maybe both tanks were feeding the one engine. So yeah I’ll get down there and trace lines and draw a diagram see what’s going on.

There are valves down on the bottom of each tank as well to shut off the tanks. The fuel lines go under the battery bank to, and hard to tell which is which. I’ll sort it out. Seen pics of other GB engine rooms and they have the same type of fuel manifold set ups, so thought someone might be in the know.

Would like to in the future redo it all with a bit of a polishing set up.

Thanks for checking guys

 

[SteveK]

Joe,
That looks familiar to me.
Those round valves normally should both be closed. If both are open an engine can draw from both sides, and/or from middle. There should be a valve at bottom of middle pipe from middle tank, which also is normally shut.
These old boats drew fuel from the bottom outside of the tank. Shut off the tank where it exits at bottom for the one you do not want and open the 2 rounds from where you want to draw. If those 2 pictured will come from opposite tank.
The returns had me head scratching as they appear to return to side tank or middle tank, never stopped to figure out how it gets to other side tank. But you have Lehman so very little returned anyway.

 

[GrandWood]

Joe,
That looks familiar to me.
Those round valves normally should both be closed. If both are open an engine can draw from both sides, and/or from middle. There should be a valve at bottom of middle pipe from middle tank, which also is normally shut.
These old boats drew fuel from the bottom outside of the tank. Shut off the tank where it exits at bottom for the one you do not want and open the 2 rounds from where you want to draw. If those 2 pictured will come from opposite tank.
The returns had me head scratching as they appear to return to side tank or middle tank, never stopped to figure out how it gets to other side tank. But you have Lehman so very little returned anyway.

Thank you Steve, we’re headed out tomorrow on a 8/10 day cruise of the south sound, so I’ll just experiment switching tanks using the main valves on the bottom of the tanks and see how that goes. Really want to get the center tank empty to cut it out and give myself more storage space below. Will be a winter project, as I’d like to move the electrical rearward as well once tank is out.

 

[SteveK]

Open three round valves on board, open center tank valve at bottom of tank, close SB and port at bottom of tanks and leave returns as they are unless side tanks are recently filled full.

 

[GrandWood]

Open three round valves on board, open center tank valve at bottom of tank, close SB and port at bottom of tanks and leave returns as they are unless side tanks are recently filled full.

Thank you Steve, works great, so pretty much just turn off whatever tank you don’t want to use. Can even run off two tanks on one engine and they go down even. Much appreciated