twin fuel tank set up

P

pakama

New Member
Jun 3, 2017
16
Florida
Boat Info
1988 300 Weekender (current)
1988 270 DA (past)
1990 250 DA (past)
1988 Laguna (past)
Engines
twin 5.7l mercruiser inboards
looking for knowledge on best way to connect 2 fuel tanks. 88 300 WE, twin 5.7 mercs inboards. 2*100 gal tanks sit out board of engines with fuel lines and 2 filters per side (1 by each tank, 1 on each motor) plumbed directly to fuel pump on each motor. This is the first multitank set up I've had that was not connected with valves to shut off and switch tanks- makes no sense to me why it was rigged this way:huh:. Is this normal on this model? If so, why? Anybody have good way to connect the two so you can run of either side or both?
Thanks in advance!
Matt
 
I had two 1996 330 Sundancers (first one got totaled when I was hit by a BUI boater). One had a fuel manifold, the other did not. The manifold was pretty simple. You could run both engines off one tank or both tanks. I'm going from memory here, but IIRC this is what the manifold system looked like:

The blue circles are on/off switches, simple ball valves that rotated 90* to shut them off. I never quite understood why you would want to shut off fuel to one engine, but I guess if that carb sprung a leak or something it might come in handy.

Gas Manifold.jpg

I hope this helps.
 
Thanks, that's about how I will do it. It's just that I keep mine in back of my house in a canal and usually gas up with a caddy. It's a real PITA to have to turn the boat around to gas the other side. I know it helps balance the boat to keep them about equally filled so I like to keep one full and just run on and refill the one dockside. Then if I need it I can switch to the other. BTW- I like your boat.
 
pakama, the diagram I drew above doesn't allow pumping fuel from one tank to the other to balance the load. You could do that with one electric fuel pump and the ability to switch it from one tank to the other. You wouldn't need to have a reversible pump though that would probably make it easier. With a pump that won't reverse, you just need to reverse the tank that it's drawing from and the tank it's pumping into.

Thanks for the comment about the boat. I feel the same way about it.
 
When I bought my boat, the dealer told me it had every option Sea Ray offered except for the crossover fuel system. He said they never order that option on the gas boats because the valves inevitable leaked, which creates an extremely hazardous condition. In all the years I've owned the boat, I never really wished I had the option.
 
It's normal practice (and maybe required by ABYS and CE) that fuel pickups come from the top of the tank, drawing from a dip tube. The only exception would be on a diesel boat - a sight glass or drain/transfer connection which would require a valve welded, or threaded, directly onto the tank. Because we draw fuel up and out, the plumbing itself won't cause the tanks to self level.

You could add a pump to move fuel the way you describe, but I'm not aware of any other safe way to do it.
 
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