Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 20-05-2008, 10:39   #1
Registered User

Join Date: Sep 2006
Location: Charlotte, NC
Boat: Voyage 38 Catamaran
Posts: 25
Tank Gauges - Help!

I have two fuel tanks and two water tanks. The fuel tanks have one analog gauge with a switch to choose which tank to display and the water tanks have a gauge and a switch with the identical setup. The two gauges and switches are independent of each other. All tanks show a reading on the gauge but none of them are correct. Some will decrease as the fluid is used but none of them show the correct amount. I have no idea how to troubleshoot this! I have my multi-meter in hand. What should I see at different locations? Other ideas? Any help would be greatly appreciated!!!!! Thanks.
Dan
Alegria
__________________

__________________
svAlegria is offline   Reply With Quote
Old 20-05-2008, 11:16   #2
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,150
Dan,
First, make sure the gauges and sending units are getting good voltage and all your terminals are tight and free of corrosion. Use a multimeter to check for continuity through the wires and check for resistance where there should be little to no resistance.

Other than that, there could be two more problems. Either there is a problem with the gauge or there is a problem with the sending unit...or both.

The sending unit inside the tank may be stuck or partially stuck. In that case it is best to remove it and get another one. I have had stuck sending units before and I think it is best to replace them rather than try to monkey with them to get them to work again. You can confirm a bad sending unit by placing your ohm meter across it and then drain the tank. Does the resistance change smoothly or does it not change at all or do a sudden rapid change? If so to the last two, the sending unit is stuck or partially stuck. Also, does the float actually float?

As far as the meter goes, the way to test this is to attach it to a sending unit that you know works and with the sending unit out of the tank, move the float up and down by hand. Does the reading on the meter change? Does it say empty, half and full in accordance to what the sending unit is telling it?

David
__________________

__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 20-05-2008, 11:17   #3
Registered User
 
JiffyLube's Avatar

Join Date: Mar 2008
Location: Oceanside, Ca.
Boat: Islander Freeport 36
Posts: 567
Images: 8
Quote:
Originally Posted by svAlegria View Post
I have two fuel tanks and two water tanks. The fuel tanks have one analog gauge with a switch to choose which tank to display and the water tanks have a gauge and a switch with the identical setup. The two gauges and switches are independent of each other. All tanks show a reading on the gauge but none of them are correct. Some will decrease as the fluid is used but none of them show the correct amount. I have no idea how to troubleshoot this! I have my multi-meter in hand. What should I see at different locations? Other ideas? Any help would be greatly appreciated!!!!! Thanks.
Dan
Alegria
I have a level gauge in my waste holding tank, and to get proper readings a high and low setting must be made first. I had to set one level limit while the tank was empty (low setting), and one setting for the high limit while the tank was full (high setting)...in my case with the waste tank I used water for setting the high limit. Maybe your system requires that to be done for each holding tank being used.
__________________
JiffyLube is offline   Reply With Quote
Old 20-05-2008, 11:27   #4
Registered User
 
Stranded Mariner's Avatar

Join Date: Sep 2007
Location: Shanghai, China
Boat: Dix 43 CC, steel, 43 ft
Posts: 149
Send a message via Skype™ to Stranded Mariner
Good advice from David.
Speaking for myself, on the boat that I am having built now, there will be no level gauges. Too many issues with those. I am going back to good old fashioned sounding pipes and tank tables.
__________________
'How inappropriate to call this planet Earth when it is quite clearly Ocean.' - Sir Arthur C. Clarke
Stranded Mariner is offline   Reply With Quote
Old 20-05-2008, 11:31   #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: 31,577
Images: 240
TESTING FLOAT TYPE LEVEL GAUGES:
Fuel, Water, Sewerage, et al

1. Remove Sender Wire from “S” Terminal on Gauge, and Turn ON Instruments Circuit.

2. Test Voltage between “I” Terminal (External Power Supply) and Ground Terminal “G”.
Tested voltage must match nominal voltage of the Gauge (ie: 12V Gauge must test between 10 - 16VDC), and the Battery Voltage.
If no voltage - check Ignition or Instrument Switch(s) and/or Fuses.
If tests less than battery voltage, repair or replace (Violet) wire from Ignition or Instrument Switch.

If a Sender fails “Open” (Infinite Resistance), one or both (if Dual Station) Gauges will read Zero Scale.
If a Sender Fails “Closed” (shorted - Zero Resistance), one or both Gauges will read Full Scale.

Other confusing Ohmmeter results, such as readings lower than expected, could indicate a poor Ground Connection at the Sender Body (Sender to Engine Block). Check for pipe dope or tape on Sender Threads.

Remember, a Float Switch gauges the Level in a tank, and will only be accurate if the tank is symmetrical.

Level Gauges (Float):

1. Disconnect Sender Wire from Gauge, and turn power ON.
The Tank Gauge should read ZERO Scale (< Empty)

2. Short the Gauge Sender Terminal to Ground.
The Gauge should read FULL Scale (> Full).

3. Measure resistance of Sender Wire to Ground.
American Floats: 240 Ohms (Empty), 103 Ohms ( Full), & 33 Ohms (Full)
European Floats: 10 Ohms (Empty), 95 Ohms (Half), & 180 Ohms (Full)
Automotive & other Float Switches may use other resistances such as 0 - 90 Ohm, 73 - 10 Ohm, & etc.

See also:
http://www.cruisersforum.com/forums/...sting-645.html

And:

Wiring Diagrams:
http://www.cruisersforum.com/gallery...=500&userid=79

Testing Instructions:
http://www.cruisersforum.com/gallery...=500&userid=79

Sender Resistance:
http://www.cruisersforum.com/gallery/showimage.php?i=1624&c=500&userid=79
__________________
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 online now   Reply With Quote
Old 20-05-2008, 11:59   #6
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,150
Quote:
Originally Posted by Stranded Mariner View Post
Good advice from David.
Speaking for myself, on the boat that I am having built now, there will be no level gauges. Too many issues with those. I am going back to good old fashioned sounding pipes and tank tables.
Nice idea. I also like the opaque plastic tanks where you can actually see the fluid sloshing around inside. We have a boat at work that uses one of those tanks. We don't even bother with a fuel gauge for that boat. I can though see the necessity for a gauge if getting to the tank is a pain.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 20-05-2008, 20:42   #7
Registered User
 
Stranded Mariner's Avatar

Join Date: Sep 2007
Location: Shanghai, China
Boat: Dix 43 CC, steel, 43 ft
Posts: 149
Send a message via Skype™ to Stranded Mariner
Quote:
Originally Posted by David M View Post
Nice idea. I also like the opaque plastic tanks where you can actually see the fluid sloshing around inside. We have a boat at work that uses one of those tanks. We don't even bother with a fuel gauge for that boat. I can though see the necessity for a gauge if getting to the tank is a pain.
Because I have steel tanks for both fuel and water, integrated in the keel, I am thinking about round sight glasses in the tank lid, of about 15 cm (about 6") diameter. I have seen them before, and it makes it easy to do some basic visual inspection of the tank, without unscrewing 50+ nuts and/or bolts of the tank lid.

And yes, if the tanks are hard to access, some type of remote gauge is the only choice.
__________________
'How inappropriate to call this planet Earth when it is quite clearly Ocean.' - Sir Arthur C. Clarke
Stranded Mariner is offline   Reply With Quote
Old 21-05-2008, 02:02   #8
Senior Cruiser
 
Lancerbye's Avatar

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Ladysmith,BC, Vancouver Island , Canada
Boat: Lancer 44 Motorsailer
Posts: 1,757
Images: 32
The Tank tender that I have on the boat can measure four tanks, nothing electric,simple backpressure measurement converted on the gauge. One scale for diesel and a second one for water. All in inches. A chart mounted below converts the info to gallons. Very simple and very accurate.
__________________
The basis of accomplishment is in never quitting
Mengzi Meng-tse
Lancerbye is offline   Reply With Quote
Old 21-05-2008, 05:08   #9
Registered User
 
Stranded Mariner's Avatar

Join Date: Sep 2007
Location: Shanghai, China
Boat: Dix 43 CC, steel, 43 ft
Posts: 149
Send a message via Skype™ to Stranded Mariner
Backpressure measurement is very reliable and simple to set up. One of the things my company does is selling tank level gauging equipment.

Some of it is based on ullage measurement (the free space above your fluid level). It is basically a radar transmitter at the top of your tank.

The other system is simple backpressure measurement. It is the cheaper and more reliable option.
__________________
'How inappropriate to call this planet Earth when it is quite clearly Ocean.' - Sir Arthur C. Clarke
Stranded Mariner is offline   Reply With Quote
Old 21-05-2008, 11:35   #10
Senior Cruiser
 
Lancerbye's Avatar

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Ladysmith,BC, Vancouver Island , Canada
Boat: Lancer 44 Motorsailer
Posts: 1,757
Images: 32
About Tank Tender This is the system I was talking about.
__________________
The basis of accomplishment is in never quitting
Mengzi Meng-tse
Lancerbye is offline   Reply With Quote
Old 22-05-2008, 23:18   #11
Registered User
 
Stranded Mariner's Avatar

Join Date: Sep 2007
Location: Shanghai, China
Boat: Dix 43 CC, steel, 43 ft
Posts: 149
Send a message via Skype™ to Stranded Mariner
Thanks Lancerbye, looks quite interesting and easy.
__________________
'How inappropriate to call this planet Earth when it is quite clearly Ocean.' - Sir Arthur C. Clarke
Stranded Mariner is offline   Reply With Quote
Old 28-05-2008, 21:58   #12
Senior Cruiser
 
Toys_with_time's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: Summer 1 sailing in the Aegean, summer 2 in Australia (earning $ to pay for summer 1)
Boat: FP Lipari 42, Katmazu
Posts: 218

[quote=David M;164597] I also like the opaque plastic tanks where you can actually see the fluid sloshing around inside.


I'm not sure I want that for my black water tank - too much information
__________________
Toys_with_time is offline   Reply With Quote
Old 28-05-2008, 22:06   #13
Senior Cruiser
 
Therapy's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: W Florida
Boat: The Jon boat still, plus a 2007 SeaCat.
Posts: 6,894
Images: 4
[quote=Toys_with_time;166806]
Quote:
Originally Posted by David M View Post
I also like the opaque plastic tanks where you can actually see the fluid sloshing around inside.


I'm not sure I want that for my black water tank - too much information
Better than a dip stick!
__________________
Therapy is offline   Reply With Quote
Old 28-05-2008, 22:10   #14
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,150
Not clear...opaque. You can't see the "wrinkle fish" but you can see how much water they have to swim around in.
__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 29-05-2008, 05:30   #15
Senior Cruiser
 
Lancerbye's Avatar

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Ladysmith,BC, Vancouver Island , Canada
Boat: Lancer 44 Motorsailer
Posts: 1,757
Images: 32
There is no liquid or other stuff in the lines going back to the gauge. You are measuring back pressure caused by the depth of the material. Only air in the lines.
__________________

__________________
The basis of accomplishment is in never quitting
Mengzi Meng-tse
Lancerbye is offline   Reply With Quote
Reply

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
existing tank ksmith Engines and Propulsion Systems 3 30-03-2008 19:51
gravity tank rebel heart Plumbing Systems and Fixtures 17 03-01-2008 18:59
Need to Replace Gauges! stoupidmonkey Engines and Propulsion Systems 16 31-10-2007 08:51
Tank Tender slow shoes Construction, Maintenance & Refit 23 15-04-2007 06:44
Installing Engine Gauges? exposure Engines and Propulsion Systems 6 28-11-2006 05:21



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 07:29.


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.