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Thread: 2nd tank issue

  1. #1
    Member c6 batmobile's Avatar
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    Default 2nd tank issue

    My boat has 2 tanks. I have them connected to a 3 port switch over valve (basically a solenoid) and a switch that selects the tank and picks up the sending unit to a single gauge.

    I was having some issues with the 3 port valve power but I cleaned that up yesterday morning and you can hear the valve actuating and the sending units pick up. I also blew air into the pickup line to make sure there wasn't something in the tank pick up tube and you could hear the tank bubbling.

    I added a bottle of heet to both tanks since I have been having issues with the one figuring maybe water.

    Ran the boat down the tanana yesterday on the "bad" tank. Had no issues. Figured my problem was solved. Sat on my bear bait for a few hours. Start boat up. Warms up. Take off and jump on step still on the bad tank. Runs for maybe 1/4 mile and starts to sputter. Switch tanks and now runs fine.

    Should I just Give up on the fuel in there and drain it completely and try it again? I've managed to burn about 6 gallons of the 20 in there but I can't get it running long enough on that tank to burn through whats in there. Is it possible there is a blockage in the tank? I can't see anything past the baffle in there and the gas looks pretty clean.

    Any suggestions?
    Makin fur fins and feathers fly.

  2. #2
    Member 0321Tony's Avatar
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    Check the vent to that tank. if its not venting you could be pulling a vacuum and restricting fuel. Any way to bypass the switch over valve to eliminate the possibility of having something faulty in the valve itself? Also check for a crack or hole in your fuel line.
    Will it idle on that tank and just not run up to full power or will it not run at all?
    You could also drain the tank, save the fuel and if it fixes the problem use the gas to start a fire. if your problem is still there you have spare gas you were going to use anyways.

  3. #3
    Member mudbuddy's Avatar
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    Could be some dirt/leaves/stuff in there that takes some time while slooshing around to
    plug up & reduce the flow.
    A hard one to fix if you can't get in there & see what's happening.

    Maybe a bigger line with an online filter right after the tank to see if you have suspend particles
    causing the problem.

    Some tanks have a screen filter inside the tank that can plug .

  4. #4

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    You could have a hole or crack in you pick up tube in the tank

  5. #5
    Member Akgramps's Avatar
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    Racors are handy because you can see any water that may have ended up in the tank, connections can be a issue, I have two tanks and had a "whip" on the motor with a quick disconnect on each tank so it was easy to swap, starting having fuel issues on the Yukon and thought it was bad fuel even though the Racor was clean. I changed the filer anyway, problem persisted. Discovered it was one of the QD's leaking (sucking air). I ended up eliminating the QD's except for one on the Racor that I never remove, then plumbed the tanks directly to the Racor with a ball valve at the Racor for each tank. So far so good...
    “Nothing worth doing is easy”
    TR

  6. #6
    Member c6 batmobile's Avatar
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    Quote Originally Posted by tinboat View Post
    You could have a hole or crack in you pick up tube in the tank

    I have considered this.

    It runs great at idle just when I power up it starts sputtering. I can run it to about half throttle before it really starts giving me fits.

    Its an older duckworth. Do those tanks typically have a welded pickup tube in the tank?
    Makin fur fins and feathers fly.

  7. #7
    Member theultrarider's Avatar
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    I just had a similar fuel issue this weekend out in the sound. Moor would run perfect, then just like someone turned the key off die. Then start right back up. Mine is an inboard with efi so the electric fuel pump would cycle and draw enough fuel to restart it. I finally pulled the puckup tube out of the tank to check that off the list as others have suggested above. Well.... the tube was fine however about an inch in from the end of the tube is a wire mess screen. The last inch of my pickup tube was plugged off almost solid with algea that it had sucked up out of the tank! Clean out the tube. Reinstalled. And runs like a top. Ran another 30 miles zero issues. Time to flush that tank. I dont want to repeat that again.

  8. #8

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    I'm confused... is there an algae that grows in fuel? I've never heard of such a thing, I would think it would be too toxic for life in there. How are people getting algae from their tanks?

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    Quote Originally Posted by grantypoo View Post
    I'm confused... is there an algae that grows in fuel? I've never heard of such a thing, I would think it would be too toxic for life in there. How are people getting algae from their tanks?
    Grows in diesel. Takes water and a little bit of warmth. It’s very real, and a serious pain in the behind.

  10. #10

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    Interesting. This is good to know... I've got a 3/4 ton diesel truck and I've never had an algae problem but now I'm worried about it

  11. #11
    Member theultrarider's Avatar
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    Yes. It is very real. Mostly with diesels. Home heating tanks as well. But can grow in gas tanks as well. Usually it is a sign of water in your fuel. Good clean fuel and you dont generaly have that issue. Pickup trucks and Semi trucks also will fight algea when getting a tank of poor fuel. Seafoam and other fuel treatmants help to kill it and break it up.
    However the next problem hapens at that point. You plug up filters and injectors like crazy till its all out of the tank.

    If you google "how to clean a boat fuel tanks" several videos pop up with a pretty simple setup to filter out your fuel at home.

  12. #12
    Member c6 batmobile's Avatar
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    Im still getting my butt whipped by this second tank.

    I took a slightly smaller tube and slipped it inside the old pickup tube. I used a flared end and put a small dab of JB weld around the top to hold it in place. This did let the boat run on the tank but still couldn't throttle up.

    I then replaced the hose. No gain in performance.

    I then replaced the fitting going into the top of the tank. No gain in performance.

    Next I stuck a small O-ring in between the fitting and the new pick up tube. I can get the boat up to about 3k rpm (normal is 4-4400) but no higher or it starts to sputter and die.

    I have absolutely gorilla torqued the fitting into the top of the tank to try and make sure its getting a good seal. Could the smaller diameter tube not be supplying the fuel I need on the top end now?

    Also I noticed something odd about my setup the other day. The tanks were running to a 3 port valve and on the other side of the valve to the filter and then the motor. Before the filter there is a 3 way "T" fitting that has a vent. Both tanks are vented. Is there a reason for this additional vent? Is it needed?
    Makin fur fins and feathers fly.

  13. #13
    Member Akgramps's Avatar
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    Need a pic of that.
    “Nothing worth doing is easy”
    TR

  14. #14
    Member KantishnaCabin's Avatar
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    Quote Originally Posted by c6 batmobile View Post
    Im still getting my butt whipped by this second tank.

    I took a slightly smaller tube and slipped it inside the old pickup tube. I used a flared end and put a small dab of JB weld around the top to hold it in place. This did let the boat run on the tank but still couldn't throttle up.

    I then replaced the hose. No gain in performance.

    I then replaced the fitting going into the top of the tank. No gain in performance.

    Next I stuck a small O-ring in between the fitting and the new pick up tube. I can get the boat up to about 3k rpm (normal is 4-4400) but no higher or it starts to sputter and die.

    I have absolutely gorilla torqued the fitting into the top of the tank to try and make sure its getting a good seal. Could the smaller diameter tube not be supplying the fuel I need on the top end now?

    Also I noticed something odd about my setup the other day. The tanks were running to a 3 port valve and on the other side of the valve to the filter and then the motor. Before the filter there is a 3 way "T" fitting that has a vent. Both tanks are vented. Is there a reason for this additional vent? Is it needed?
    At this point I'd be looking at your fuel pump. Perhaps its just a little old and tired. You could consider adding an electric fuel pump after your 3 way valve just to relieve some of the stress on your main pump at the engine. I'm assuming this is the old mechanical diaphragm pump on the block and its original?

  15. #15
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    Quote Originally Posted by grantypoo View Post
    Interesting. This is good to know... I've got a 3/4 ton diesel truck and I've never had an algae problem but now I'm worried about it
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  16. #16
    Member c6 batmobile's Avatar
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    Quote Originally Posted by KantishnaCabin View Post
    At this point I'd be looking at your fuel pump. Perhaps its just a little old and tired. You could consider adding an electric fuel pump after your 3 way valve just to relieve some of the stress on your main pump at the engine. I'm assuming this is the old mechanical diaphragm pump on the block and its original?
    It is the old style mechanical diaphragm pump. Don't know the age. I works fine on the driver side tank just not so much on the passenger side tank. I can give that a whirl but Im just throwing money and time at it right now.
    Makin fur fins and feathers fly.

  17. #17
    Member avidflyer's Avatar
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    I was dealing with junk in my tank as well. I picked up a facet pump and plumbed it inline and was pumping it into jugs to empty the tank. I used clear line so I could see what was going through it. I was seeing air bubbles in the line and of course started at the tank and worked to the back of the boat. Turns out the powder coating on the fuel filter was failing allowing it to suck air in around the top of the filter (but gas was not leaking out of it). Scraped the housing off and spun the filter back on and no more issues! This was an issue I had been fighting off and on for 2 yrs.

  18. #18
    Member KantishnaCabin's Avatar
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    Well it can only really be one of three or four things. Blocked pick-up and supply line, blocked vent on the tank, cracked fuel line or bad fuel pump. One of these things is not allowing good fuel pressure past the three way valve. I would bet that your "good" tank is closer to your 3 way valve and therefore a shorter draw for your pump. Those mechanical pumps need to be changed over time. The diaphragm can get small cracks in it and it wont pump as efficiently as they age. Newer V-8's all have electrical fuel delivery systems, partly because they operate at higher pressures and partly because of reliability. When you are running off of multiple fuel tanks and drawing through a 3way valve and also a racor its not a bad idea to have an electrical pump as an assist to you mechanical.

  19. #19
    Member c6 batmobile's Avatar
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    Quote Originally Posted by KantishnaCabin View Post
    Well it can only really be one of three or four things. Blocked pick-up and supply line, blocked vent on the tank, cracked fuel line or bad fuel pump. One of these things is not allowing good fuel pressure past the three way valve. I would bet that your "good" tank is closer to your 3 way valve and therefore a shorter draw for your pump. Those mechanical pumps need to be changed over time. The diaphragm can get small cracks in it and it wont pump as efficiently as they age. Newer V-8's all have electrical fuel delivery systems, partly because they operate at higher pressures and partly because of reliability. When you are running off of multiple fuel tanks and drawing through a 3way valve and also a racor its not a bad idea to have an electrical pump as an assist to you mechanical.

    Both have the same distance of line to the "T". I assumed a blockage at first so I back flushed the line with air and drained the tank a week later. The gas was pretty clean. I put a new fuel line and elbow fitting on the tank assuming that was the next place air could get it. I also checked the vent line and blew it out with air. Nothing in it. I thought the crack might be in the pickup tube and thats why I put a smaller diameter tube in there. Is it possible the 5/16 diameter tube wont supply sufficient fuel for the demand?

    My concern is if I add an electric pump it will still just pump the air bubbles now just faster.
    Makin fur fins and feathers fly.

  20. #20
    Member KantishnaCabin's Avatar
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    I recently replaced my fuel pump for my 94 Jetcraft with a 5.7L Kodiak. I want to say that it was $70 at Fats Autoparts here in anchorage. I actually bought the pump last year as a just in case spare before I went hunting last year. This year I swapped them and now have the old one in a ziplock as a back-up. You can use the automotive pumps, so any parts house will have them in stock.

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