Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 13-12-2014, 14:23   #1
Registered User
 
crowlegs's Avatar

Join Date: Jun 2012
Posts: 12
Novice trying to figure out fresh water pressure issue

Greetings all...

I've got a Shurflo 4000 model 804-009-01 and over the last few months, I've noticed that the pump will kick on to pressurize the collection tank while no water is being used anywhere on the boat. So, there's probably a leak either on the pump/tank or in a fresh water line. I don't find any water where it shouldn't be along the fresh water lines, so my guess is the pump/collector. Has anyone else had this problem with a similar setup and how did you remedy the problem?

The second issue is that the pump won't consistently pull water up from the lower of my 3 water tanks and the pump just runs and runs until I turn on one of the higher placed tanks. All three tanks feed into a piece of stainless which has two outputs, one to the hand pumps and the other to the Shurflo system. I've taken off the feed and vent on the lower tank and blown air through each hose and none of them feel restricted. To get the lower tank to feed water, I have to turn on a higher tank until I see water backflowing into the lower tank. I assume then that there is no air trapped between the tank and the stainless flow control piece. Once I turn on the faucet, the water will run nicely for about 5 mins, then the pitch of the pump motor changes to a higher note and the water flow eventually dwindles down to nothing.

Any observations, instructions or suggestions would be greatly appreciated!

Thanks everyone.
__________________

__________________
crowlegs is offline   Reply With Quote
Old 13-12-2014, 21:59   #2
Registered User

Join Date: May 2011
Boat: Hitchhiker, Catamaran, 40'
Posts: 354
Re: Novice trying to figure out fresh water pressure issue

You have a leak in the lower feed line that is sucking air (does the tank have a dip tube?) and you either have a leak on the pressure side or a bad check valve in the pump. If it is the pump check valve you could install an external check valve on the pressure side of the pump.
__________________

__________________
Thumbs Up is offline   Reply With Quote
Old 13-12-2014, 22:43   #3
Long Range Cruiser
 
MarkJ's Avatar

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Australian living on "Sea Life" currently in England.
Boat: Beneteau 393 "Sea Life"
Posts: 12,828
Images: 25
Re: Novice trying to figure out fresh water pressure issue

A tiny leak can spray mist so fine it never settles so it drip. There are difficult to find.
__________________
Notes on a Circumnavigation.
OurLifeAtSea.com

Somalia Pirates and our Convoy
MarkJ is offline   Reply With Quote
Old 13-12-2014, 23:41   #4
Marine service provider
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 4,025
Re: Novice trying to figure out fresh water pressure issue

It sounds like a hoseclamp needs to be tightened on the feed line from the tank and the pump check valve is leaking by and allowing pressure to drop you can install new check valve inline or now that you know the reason for the pump cycling its not a problem won't cause the pump to fail and usually happens to all pressure pumps eventually
__________________
newhaul is online now   Reply With Quote
Old 14-12-2014, 04:56   #5
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,592
Images: 240
Re: Novice trying to figure out fresh water pressure issue

Greetings and welcome aboard the CF, crowlegs, and newhaul.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 14-12-2014, 13:51   #6
Marine Service Provider

Join Date: Sep 2008
Location: Victoria B.C.
Boat: CS27
Posts: 1,743
Re: Novice trying to figure out fresh water pressure issue

Quote:
Originally Posted by crowlegs View Post

The second issue is that the pump won't consistently pull water up from the lower of my 3 water tanks and the pump just runs and runs until I turn on one of the higher placed tanks.
Pumps always push better than they draw. The pump should not be mounted higher than the tank ideally.
__________________
mitiempo is offline   Reply With Quote
Old 17-12-2014, 14:29   #7
Registered User

Join Date: Aug 2012
Posts: 2
Re: Novice trying to figure out fresh water pressure issue

I agree with the other posts that a small leak is probably the issue. In the case where your water tank is below the pump and the pump suction must draw the water up to a higher elevation net positive suction head, NPSH, is a common issue if the water is warm such that vapor pressure is lowered allowing vapor to form in the lower pressure suction line. The pump then cavitates as vapor replaces liquid and suction is lost. You can have a similar problem due to pressure drop in the inlet pipe if it presents excessive flow resistance due to tight bends or long lengths of small diameter tubing.
__________________

__________________
Harvey Mason is offline   Reply With Quote
Reply

Tags
novice, water

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Baja Malibu. Well I have a boat now I'm trying to figure out how to keep it Moltensurf Meets & Greets 16 01-12-2013 14:40
Newbies to Med trying to figure out phone plans lhsmith Europe & Mediterranean 20 18-03-2013 10:53
Discouraged and Trying to Figure Out How to Get into Sailing Sub Nate Meets & Greets 36 06-12-2010 20:15
Trying to figure out some things rscottm Meets & Greets 11 10-01-2008 13:06



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 10:42.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.