8.1 Fuel drains continuously when changing filter

Discussion in 'General Maintenance/Repair Questions' started by R-and-R, May 22, 2020.

  1. R-and-R

    R-and-R Member SILVER Sponsor

    119
    May 9, 2018
    2002 340 Sundancer
    8.1S Mercruiser
    When changing my filters I typically get a few ounces of fuel spillage. Enough that I can catch it with a small container and shop towels.

    But on my most recent change on my port motor, the fuel practically gushed continuously until I could get the new filter spun on. Engine switch was definitely in the Off position, so fuel pump was not powered.

    I'm thinking maybe the fuel shutoff valve from the tank is stuck open?
    Any ideas how to test?
    Or other problems to look for?
     
  2. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Quite possible if you have the electric valves. Could be the anti-siphon valve if you have the older setup

    I think you already tested it, and it's open.
     
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  3. techmitch

    techmitch Well-Known Member GOLD Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    Yep, or the vent could be clogged.
     
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  4. stephenm27

    stephenm27 Active Member

    382
    Nov 3, 2009
    Milton, GA
    2009 310 Sundancer
    350 MAG Mercs/B3 x 2 (Axius Premier)
    The original Parker Hanafin anti-siphon valves on my boat have a knurled knob that can be turned to ‘bypass’. If this is done and you don’t break the siphon, I could see how you’d see continuous fuel flow assuming your tank is higher the the hose end.
     
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  5. R-and-R

    R-and-R Member SILVER Sponsor

    119
    May 9, 2018
    2002 340 Sundancer
    8.1S Mercruiser
    Is this the valve we’re talking about?

    I can turn the knob manually, but it doesn’t move when I turn the ignition on and off. Should it?

    9E7524D1-BD93-4B44-A0AD-6EBD1806E759.jpeg
     
  6. stephenm27

    stephenm27 Active Member

    382
    Nov 3, 2009
    Milton, GA
    2009 310 Sundancer
    350 MAG Mercs/B3 x 2 (Axius Premier)
    Yes, that is the valve. The knob is only moved manually. It provides an override in case the valve fails in the closed (non-energized) position.

    If you look (very) closely, the words “normal” and “bypass” are engraved on the valve body and there is a arrow (not to be confused with the slot) on the knob itself to indicate where the knob is currently positioned.

    In normal mode, 12vdc opens the valve, closes with no voltage. In override, valve is always open (physically manipulated via the knob).
     
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  7. R-and-R

    R-and-R Member SILVER Sponsor

    119
    May 9, 2018
    2002 340 Sundancer
    8.1S Mercruiser
    Thanks guys.

    I was suspicious of that valve. Good to have some confirmation before I replace it.
     
  8. stephenm27

    stephenm27 Active Member

    382
    Nov 3, 2009
    Milton, GA
    2009 310 Sundancer
    350 MAG Mercs/B3 x 2 (Axius Premier)
    Do you believe it has failed? Normally, the failed mode is closed and you get no fuel flow. I don’t think they fail open which is why I was suggesting verifying that it’s simply not in bypass mode.

    If it has indeed failed, you may have issues finding a replacement, unless going through a SR dealer. I found the part numbers on the valves to be mostly decipherable using old PH literature but there were some elements of the number that appeared to be custom to SR and thus couldn’t determine their meaning/spec.

    I was able to determine my valve did not need replacement...
     
  9. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Check for voltage at the valve with key on.
     
  10. R-and-R

    R-and-R Member SILVER Sponsor

    119
    May 9, 2018
    2002 340 Sundancer
    8.1S Mercruiser
    Now that you mention it, I need to recheck the position of the manual knob. It may have been in the Bypass position.
    Do you have a cross reference number for Parker V5C72120?
     
  11. stephenm27

    stephenm27 Active Member

    382
    Nov 3, 2009
    Milton, GA
    2009 310 Sundancer
    350 MAG Mercs/B3 x 2 (Axius Premier)
    No--I was unable to decode the valve part # using Parker's literature. I eventually gave up once I determined my valve was not faulty.
     
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