Water pressure surge?

Discussion in 'General Discussion' started by thompsdw, Sep 17, 2012.

  1. thompsdw

    thompsdw New Member

    196
    Apr 15, 2007
    Richmond, VA
    2000 Sundancer 270
    7.4 MPI Mercruser
    Now that I have all leaks fixed and the hot water heater changed, I've noticed that the water pressure fluctuates at every tap. I can hear the pump running with water flow, and then it seems to stop (pressure drops) and then it turns back on (pressure rises). The end result is pressure at the tap that rises and falls.

    Any ideas? Pressure switch?


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  2. northern

    northern Well-Known Member

    Jan 17, 2007
    West coast Vancouver to Alaska
    380 Aft Cabin 1989 GPS and Charts by Nobeltec
    Twin 454 strait shaft
    Normal
    There is about 15 psi it seems before our pump comes back on.
     
  3. thompsdw

    thompsdw New Member

    196
    Apr 15, 2007
    Richmond, VA
    2000 Sundancer 270
    7.4 MPI Mercruser
    That helps, so to be clear ................ your faucet speeds up, slows down, speeds up, slows down, etc?
     
  4. Bucit

    Bucit New Member

    Mar 12, 2010
    St. Petersburg Florida
    2005 280 Sundancer
    2004 SPD-104 Achilles w/ 8hp Yamaha
    Twin 4.3 MPI's with Alpha drives.
    Mine doesn't do that. Once it's pressurized I could turn the pump off and still have good pressure. With the pump on it holds a pretty constant pressure all the time.
     
  5. thompsdw

    thompsdw New Member

    196
    Apr 15, 2007
    Richmond, VA
    2000 Sundancer 270
    7.4 MPI Mercruser
    That is what I thought. What I believe is happening is that the pump is cycling too quickly. I swear I hear it turn off and on quickly. Since I fixed the system (yea, right) - it doesn't seem to stay running while water is being pumped. Is the pressure sensor in the pump itself?
     
  6. Bucit

    Bucit New Member

    Mar 12, 2010
    St. Petersburg Florida
    2005 280 Sundancer
    2004 SPD-104 Achilles w/ 8hp Yamaha
    Twin 4.3 MPI's with Alpha drives.
    There is a pressure switch on the front (I believe) that's adjustable and may solve your problem.
     
  7. mistercomputerman

    mistercomputerman Active Member

    Jan 6, 2008
    Virginia Beach, VA
    410 Sundancer - 2001
    Twin 8.1L Mercruisers - 2009
    Look for an accumulator tank. It evens out the pressure.

    accumulator.jpg
     
  8. thompsdw

    thompsdw New Member

    196
    Apr 15, 2007
    Richmond, VA
    2000 Sundancer 270
    7.4 MPI Mercruser
    Don't believe I have one. Should I on my boat (above)?
     
  9. connie garcy

    connie garcy Member

    517
    May 13, 2008
    Phoenix, NY
    1999 Sundancer 370 DA
    7.4 MPI Horizon
    V Drives
    Are you hooked up to city water or are you using the water in your tank. We are having the same problem now using city water.
     
  10. thompsdw

    thompsdw New Member

    196
    Apr 15, 2007
    Richmond, VA
    2000 Sundancer 270
    7.4 MPI Mercruser
    I am on the holding tank water alone.
     
  11. mistercomputerman

    mistercomputerman Active Member

    Jan 6, 2008
    Virginia Beach, VA
    410 Sundancer - 2001
    Twin 8.1L Mercruisers - 2009
    Don't know. Check your parts manual to see if it shows one. It has a rubber bladder inside and some air and serves to even the flow. That way the cycling of the water pump does not make the water ebb and flow.
     
  12. Jimmy Buoy

    Jimmy Buoy Well-Known Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    Ensure that you are getting adequate water flow. If there are restrictions in the faucet that reduce the flow enough it can allow more pressure being built up in the line. Once the pressure gets high enough the pump stops. Then some water gets by the restriction it causes a drop in pressure and the pump cycles on once again.
     
  13. thompsdw

    thompsdw New Member

    196
    Apr 15, 2007
    Richmond, VA
    2000 Sundancer 270
    7.4 MPI Mercruser
    The primary faucet that I am flowing through is brand new.
     
  14. mistercomputerman

    mistercomputerman Active Member

    Jan 6, 2008
    Virginia Beach, VA
    410 Sundancer - 2001
    Twin 8.1L Mercruisers - 2009
    I think he was suggesting that you check the strainer/filter on the side of the pump.

    Also, if you are hooked to city water, you cut off the breaker for the boat pump.

    And, the pressure reducing valve in the back where the city water hose hooks up has been know to go bad.
     
  15. Jimmy Buoy

    Jimmy Buoy Well-Known Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    Yes, anything that restricts water can cause similar issues so checking the filter at the pump is a great idea. Also, OP did say that he is using the potable water system only - not pressurized city water which probably rules out a bad pressure valve where the city water connects.
     
  16. thompsdw

    thompsdw New Member

    196
    Apr 15, 2007
    Richmond, VA
    2000 Sundancer 270
    7.4 MPI Mercruser
    I recently cleaned the strainer. My point on the faucet is that line restrictions would have to be in the tubing itself. Although, I think some restriction is possible - I'm not sure where to look.
     
  17. mvoellinger

    mvoellinger Member

    618
    Aug 26, 2008
    Jacksonville, FL
    2002 260DA
    350 MAG w/ Bravo III
    Mine does that if I only open the faucet slightly. It basically isnt flowing enough water to keep the pump on - so the pump builds up pressure then cuts out, pressure drops a little, pump cycles back on. Its annoying, so I find myself opening the faucet up more than I may need just to keep the pump running.
     

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