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HELP! Fuel venting/transfering itself '95 50' Hatteras 12v183s

Discussion in 'Hatteras Yacht' started by CTdave, Aug 22, 2017.

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  1. CTdave

    CTdave Senior Member

    Joined:
    Mar 21, 2004
    Messages:
    855
    Location:
    Greenwich CT/ Stuart FL
    Hi all.......
    I'm having a strange problem that developed. I can fill both rear and forward tanks then leave Supply and Return on the same tank OR
    I can have the front tank empty, fill the rear, run everything to/from the rear but the forward tank will fill up & being smaller, it will start venting out once it;s full.
    Nothing has been changed as far as hoses since this started. The only thing I can see is these fuel management manifolds and possibly something going wrong inside If you look close (not the best shots, there are two vertical cylinders that might have some sort of valve inside? Something stuck? Two years ago just before the issue started, I had shaft packings going bad & they were leaking pretty good & over the winter (in the water), the power went dead for a few days & the bilge filled with a LOT off water, enough to short batteries and these manifolds were under the toxic soup.
    You are looking at the left side of the photo going aft, right going forward. Just out of the frame on the right are the four selector valves with port supply/return and same for stbd.Top hose is port supply, second down is generator and the smallest one on the bottom is the return line (I believe)
    There is the same set up on the opposite side for the stbd. engine.
    I'm completely puzzled........??????????

    Any ideas? Thank you very much for your time!!

    Attached Files:

  2. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    13,226
    Location:
    Fort Lauderdale
    Either you have a bad valve in one of the returns, OR ive seen the impeller or check valve go bad in the fuel transfer pump
    And allow fuel to fill a tank it's not supposed to. Should be easy enough to feel. Start each motor, one at a time and photo temp the return fittings and see if they're warmer than ambient, or take each hose off of the forward tank returns and see if one is returning fuel.
  3. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    9,100
    Location:
    Satsuma, FL
    Call Paul Hall at Hatteras with your hull number. Get the fuel schematic.
    I can't imagine a check valve but that may be one in that vertical coupler.
    There could also be a broken shaft in a fuel valve.
    Unless someone has already been here / fought this, were just guessing without a whole picture or schematic.
  4. 30West

    30West Member

    Joined:
    Nov 14, 2016
    Messages:
    240
    Location:
    Holland, Michigan
    I've flown airplanes where a valve wasn't sealing, and fuel kept flowing back to the empty center tank. Lots of possibilities. Those do look like check valves, but like rcrapps says, just guessing without a schematic. Is it possible to set the valves to run the return to a tank other than the one you are drawing from?
  5. wdrzal

    wdrzal Senior Member

    Joined:
    Feb 6, 2006
    Messages:
    402
    Location:
    Baltimore
    My Guess (capital G) is there is a siphon break that's built like a drain trap, Now that trap is full of water(from the drowned engine room) allowing the siphon to continue. Or it could simply be a check valve stuck.
  6. CTdave

    CTdave Senior Member

    Joined:
    Mar 21, 2004
    Messages:
    855
    Location:
    Greenwich CT/ Stuart FL
    I don't have fuel transfer pumps so it must be the selector vslve then (I'm assuming) The only pumps I have a big fuel primer pumps which I normally leave the breakers off unless needed. Even when breakers are on, I have to push a button on the pumps to operate them.
    ou don't think it's anything to do with these manifolds?I was just curious as to the two larger diameter verticle cylinder & if they have a spring/valve inside. I was planing on taking them apart but I'm already contemplating if these are just connectors.
  7. CTdave

    CTdave Senior Member

    Joined:
    Mar 21, 2004
    Messages:
    855
    Location:
    Greenwich CT/ Stuart FL
    First, thanks rcrapps, I'll try Paul. I can't be the only one who's had this problem. I do have the blue prints for absolutely everything including the fuel system but since no hoses were changed, I think it's unlikely in that department. Paul will know though
    So I took apart the fuel line manifold (pictured) and indeed, those vertical larger diameter "pipes" are check valves. Everything seemed to be functioning properly so now I have to do the starboard side. I thought I was onto something because at first, one of the spring valves seemed to be frozen "down" but after taking the other end apart, I found that both valves operated properly. So, I'll check starboard side & see if it's something there. The bottom hoses are the return lines so if it's the other side thats frozen, that's the prob. If those are good two, then I'll check the selector valves. I've never seen one of those valves shafts break and they all feel like the same resistance. I'm assuming it's a three way ball valve inside but it's trial and error. Oh yeah, we're leaving Friday morning for Block and Montauk.
    Thanks for the thoughts and replies! You guys are always the BEST!