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06-29-2020, 08:38 AM
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#1
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Senior Member
City: Kingston Ontario
Vessel Name: On The EdJ
Vessel Model: Former 390 owner now Sundancer 380
Join Date: Dec 2017
Posts: 466
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Fuel tank not balancing
We have a Mainship 390 with 2 Tanks port and starboard. I noticed a considerable list to Port yesterday (Fuel gauge was showing just off full) yesterday we fuelled up for the first time this year, and the starboard tank took $225.00 of diesel and the Port tank only took $50.00 of Diesel. both valves are open on the Equalization line at the bottom of the tanks and both Valves are open to the Racor, . I know the generator draws from the Starboard tank but we have only run it at Launch for about 5 minuets - any thought's
__________________
Joanne & Edward Billing
M/V On the EdJ Sundancer 380
Home Port Kingston Marina in the 1000 Islands
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06-29-2020, 10:16 AM
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#2
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Guru
City: San Francisco
Join Date: Apr 2018
Posts: 3,089
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I have this problem too though to a lesser extent. There are ganged valves that will switch the source between tanks, they have two circuits because you must switch the fuel return at the same time or you will be pumping spill fuel from one tank to the other until it overflows. As long as the genset returns to the tank it is drawing from, it isn't an issue.
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06-29-2020, 11:22 AM
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#3
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Valued Technical Contributor
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,775
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Do you have twins or a single?
David
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06-29-2020, 11:37 AM
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#4
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Guru
City: Warwick RI
Vessel Name: Lollygag
Vessel Model: 34 Mainship Pilot Hardtop
Join Date: Aug 2016
Posts: 872
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Had same issue last year, turns out the port side fuel filter was clogged. Once i replaced it boat was fine.
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06-29-2020, 02:58 PM
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#5
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Senior Member
City: Kingston Ontario
Vessel Name: On The EdJ
Vessel Model: Former 390 owner now Sundancer 380
Join Date: Dec 2017
Posts: 466
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Quote:
Originally Posted by DavidM
Do you have twins or a single?
David
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Single Yanmar 6LP
__________________
Joanne & Edward Billing
M/V On the EdJ Sundancer 380
Home Port Kingston Marina in the 1000 Islands
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06-29-2020, 02:59 PM
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#6
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Senior Member
City: Kingston Ontario
Vessel Name: On The EdJ
Vessel Model: Former 390 owner now Sundancer 380
Join Date: Dec 2017
Posts: 466
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Quote:
Originally Posted by Lollygag1
Had same issue last year, turns out the port side fuel filter was clogged. Once i replaced it boat was fine.
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Only has one set of filters for both tanks going to a single engine
__________________
Joanne & Edward Billing
M/V On the EdJ Sundancer 380
Home Port Kingston Marina in the 1000 Islands
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06-29-2020, 03:06 PM
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#7
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Senior Member
City: Middle River MD
Join Date: Dec 2019
Posts: 102
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If both balancing valves are open and the tanks aren't balancing out that is the place to start. The supply/return valves shouldn't affect this.
Can you confirm the fuel level in the each tank?
What size is your crossover line?
Double check that both valves are open 100% and it's not an issue with the handle or stem.
If your crossover line is actually blocked I would be concerned that something is in the tank/line and will likely block the fuel feed to the engine at some point.
However it is more likely that there is a valve not set properly or there's another valve in the crossover link that has been closed. Maybe by a helpful mechanic in the offseason?
Can you post pictures of the valves?
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06-29-2020, 03:19 PM
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#8
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Senior Member
City: Kingston Ontario
Vessel Name: On The EdJ
Vessel Model: Former 390 owner now Sundancer 380
Join Date: Dec 2017
Posts: 466
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Quote:
Originally Posted by jhall767
If both balancing valves are open and the tanks aren't balancing out that is the place to start. The supply/return valves shouldn't affect this.
Can you confirm the fuel level in the each tank?
What size is your crossover line?
Double check that both valves are open 100% and it's not an issue with the handle or stem.
If your crossover line is actually blocked I would be concerned that something is in the tank/line and will likely block the fuel feed to the engine at some point.
However it is more likely that there is a valve not set properly or there's another valve in the crossover link that has been closed. Maybe by a helpful mechanic in the offseason?
Can you post pictures of the valves?
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Both are like this
__________________
Joanne & Edward Billing
M/V On the EdJ Sundancer 380
Home Port Kingston Marina in the 1000 Islands
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06-29-2020, 04:59 PM
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#9
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Valued Technical Contributor
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,775
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Possibly the fuel return is going to a different tank than the fuel supply is coming from. With P&S tanks feeding a single engine, the flow often favors one side. The balancing line is too small or maybe it is partially plugged to keep them even.
David
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06-29-2020, 05:04 PM
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#10
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Guru
City: Seattle
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 4,280
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What we are seeing is the shut off for the tank. There could very likely be a cross over valve some where else. I would follow the port fuel line all the way to the engine and then I would follow the return line all the way back to the tank. I suspect you will find more valves.
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06-29-2020, 06:38 PM
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#11
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Senior Member
City: Kingston Ontario
Vessel Name: On The EdJ
Vessel Model: Former 390 owner now Sundancer 380
Join Date: Dec 2017
Posts: 466
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Quote:
Originally Posted by tiltrider1
What we are seeing is the shut off for the tank. There could very likely be a cross over valve some where else. I would follow the port fuel line all the way to the engine and then I would follow the return line all the way back to the tank. I suspect you will find more valves.
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No this is the cross over - the shut off for the tanks is at the other end at the top of the tank close to the Racor, when I am changing the Racor I do not touch the valve shown just the one at the top on each tank that goes directly to the Racor
__________________
Joanne & Edward Billing
M/V On the EdJ Sundancer 380
Home Port Kingston Marina in the 1000 Islands
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06-29-2020, 06:39 PM
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#12
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Senior Member
City: Kingston Ontario
Vessel Name: On The EdJ
Vessel Model: Former 390 owner now Sundancer 380
Join Date: Dec 2017
Posts: 466
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Quote:
Originally Posted by tiltrider1
What we are seeing is the shut off for the tank. There could very likely be a cross over valve some where else. I would follow the port fuel line all the way to the engine and then I would follow the return line all the way back to the tank. I suspect you will find more valves.
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This line goes directly to the other tank with the same shut off at the other tank, Sorry the Picture for some reason is back to front
__________________
Joanne & Edward Billing
M/V On the EdJ Sundancer 380
Home Port Kingston Marina in the 1000 Islands
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06-29-2020, 08:50 PM
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#13
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Senior Member
City: St Augustine
Vessel Name: Agape
Vessel Model: Californian 45
Join Date: Feb 2020
Posts: 298
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How much is the boat listing? Maybe you need some ballast to even things out. If you list too much to one side the fuel will flow to that tank. Was your boat level at the time?
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06-29-2020, 10:44 PM
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#14
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Guru
City: Seattle
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 4,280
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Follow the fuel lines from the tanks to the engine and then the return back to the tank. There are more valves some where.
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06-30-2020, 07:38 AM
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#15
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Senior Member
City: Kingston Ontario
Vessel Name: On The EdJ
Vessel Model: Former 390 owner now Sundancer 380
Join Date: Dec 2017
Posts: 466
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Quote:
Originally Posted by Pmcsurf1
How much is the boat listing? Maybe you need some ballast to even things out. If you list too much to one side the fuel will flow to that tank. Was your boat level at the time?
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You know I think you have nailed it the boat lists to port slightly when both tanks are full, (we took the couch out which was a lot heavier), and all the Galley cupboards are on the port side, and probably as I run the engine it is drawing from both tanks and as they go down the starboard tank empties into the port tank when the boat is at rest, and increases the list, (Thus the Transfer) I am going to shut off the starboard shut off and see what fuel I put in each tank next fill up. I
__________________
Joanne & Edward Billing
M/V On the EdJ Sundancer 380
Home Port Kingston Marina in the 1000 Islands
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06-30-2020, 09:03 AM
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#16
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Senior Member
City: Solomons MD.
Vessel Name: Sun Runner
Vessel Model: 1985 Mainship 34 Trawler MK III
Join Date: Mar 2018
Posts: 488
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Might also look into the water tanks to see if they are affecting the list. Not sure how many or where they are. I know our 1985 34 trawler lists to starboard when the water tanks are empty. Batteries are on the starboard side.
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06-30-2020, 09:13 AM
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#17
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Guru
City: Kitimat, North Coast BC
Vessel Name: Badger
Vessel Model: 30' Sundowner Tug
Join Date: Jul 2012
Posts: 5,946
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Responded to your other thread. Have you checked to see if the vent line to the tank that is not emptying is plugged?
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"The most interesting path between two points is not a straight line" MurrayM
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06-30-2020, 09:16 AM
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#18
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Guru
City: San Diego
Vessel Name: Circuit Breaker
Vessel Model: 2021..22' Duffy Cuddy cabin
Join Date: Oct 2007
Posts: 6,691
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Quote:
Originally Posted by Cartouche
(we took the couch out which was a lot heavier),
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New information...different solution! Makes sense. Too many suggestions without knowing the whole story!
__________________
Done with diesel power boats! Have fallen in love with all electric!
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06-30-2020, 11:42 AM
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#19
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Senior Member
City: Middle River MD
Join Date: Dec 2019
Posts: 102
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Quote:
Originally Posted by Cartouche
You know I think you have nailed it the boat lists to port slightly when both tanks are full, (we took the couch out which was a lot heavier), and all the Galley cupboards are on the port side, and probably as I run the engine it is drawing from both tanks and as they go down the starboard tank empties into the port tank when the boat is at rest, and increases the list, (Thus the Transfer) I am going to shut off the starboard shut off and see what fuel I put in each tank next fill up. I
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Not sure if you are doing this but that crossover line is required to be closed when underway.
Also I would advise against running from both tanks at the same time with both returns open. Any flow issues and you could actually transfer all the fuel to one tank creating a very unbalanced boat. And maybe even a fuel spill. You should probably alternate every couple of hours.
BTW extra beer is always good portable ballast.
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06-30-2020, 07:59 PM
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#20
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Guru
City: Saint Petersburg
Vessel Name: Weebles
Vessel Model: 1970 Willard 36 Trawler
Join Date: Mar 2019
Posts: 7,166
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Similar problem on my Willard 36 with single Perkins 4.236 75hp and twin saddle tanks of 225 gals each, though to a lessor degree than OP. For me, boat needs to be re-trimmed - no clogs or otherwise. Over the years, she got a bit heavy on port side, which caused more fuel to flow to port side, and trim gets worse until she has 3-4 degree of trim at rest. Not much but annoying. When she's done with her refit, I'll put 150 gals in each tank then use movable lead ballast to trim her to zero degrees trim. I consider this normal after 50 years and a major refit.
Peter
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Cruising our 1970 Willard 36 trawler from California to Florida
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