Right tank keeps filling up! HELP

Discussion in 'Experienced Truckers' Advice' started by mizdageeragn, Jan 16, 2011.

  1. mizdageeragn

    mizdageeragn Medium Load Member

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    Anyone out there ever had a similar problem. The previous owner of my FLD120 had a problem develope where the right fuel tank always ends up with more fuel than the left to the point where the cap starts letting fuel run out down the side of the tank. He installed a simple little on/off valve in the LEFT side tank vent hose that you close when you fill the tanks so that the pump can only pull from the right tank while driving down the road.After the Right tank has run down to about half you can open the valve and not get any fuel running down the tank side. If the truck sits on level ground not running for several hours the tank levels while more or less equalize and the gauge will read ABOUT correct. Then as you drive down the road the truck continues to put more fuel back into the right tank which again makes the dash gauge WAY off. For instance, if the truck sits all weekend and you start the day with the vent valve OPEN and with the gauge reading at 1/2, drive 400 miles, there will be about 4 inches of fuel in the left tank with the dash gauge reading just over empty and the right tank Over half full! So then shut the valve and the truck will only pull from the right tank but you have to keep an eye on the right tank level because the gauge stays just over E. His conclusion is the return system is putting too much of the fuel back in the right side and I tend to agree. The Tanks are 150 gallon cylinder style and the tank unit is in the left tank. Question is what's not right with the system?
     
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  3. Rerun8963

    Rerun8963 Road Train Member

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    maybe the fuel return line to the other tank is clogged, collapsed, maybe even missing...???

    check all fuel lines, return lines, check the fuel caps themselves. each should have a vent check ball in them...clean the inside of the caps, maybe spray some WD 40 into the vent ball seating area...??
     
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  4. JohnP3

    JohnP3 Road Train Member

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    I take it you can see the return, and pick-up aluminum piping with a flashlight, What I have done is you loosen the fuel line to the Primary filter just a little bit, do it gradually a couple of times you do not want to kill it, that will bring air into the fuel and the return. Looking into each tank are they both getting the same amount of foam. You have to do it when the tanks are low on fuel, for the best results. also tighten the line back up and leave it run for a while to purge the system of air.
    If it is returning the same to each tank then it is a pick-up problem. Take a cloths hanger and straighten it out with a hook on the end and be sure you do not have plastic bag or piece stuck in it. I have found ear plugs in systems. Got to go
     
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  5. Flying Finn

    Flying Finn Heavy Load Member

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    The 389 I had last year did that all the time. I just switched it in the cab to pull from the right tank first. It solved the fuel leaking on the tank issue. They would equalize pretty quick so the gauge showed fairly correct.
     
  6. PurpleKW

    PurpleKW Medium Load Member

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    Had a weird situation like that in a Cornbinder... the fuel would wind up in one tank, and that tank had no operational sensor, so the truck would convince itself that its fuel tanks were both empty. Fortunately, that wasn't my regular assigned truck, so I only had to deal with that irritating situation for one cross-country trip. Not critical in terms of safety, just irritating... :biggrin_25523:
     
  7. rbht

    rbht Heavy Load Member

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    I had a truck do that and the only problem was the vent tube was plugged. How old is the truck, does it have a cross over line or a equalizer valve, if it has the valve it could be the problem also.
     
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  8. Hardlyevr

    Hardlyevr Road Train Member

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    Check the vent tubes for crud or blockage, if they are open and clear you need to replace the proportioning valve that controls the fuel returning to the tanks from the engine.
     
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  9. CondoCruiser

    CondoCruiser The Legend

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    I second that. :) It has a crossover and the driver side is pressurizing from the fuel return. Sounds like the vent tube is plugged on the drivers side.
     
  10. mizdageeragn

    mizdageeragn Medium Load Member

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    Trouble is I have no switch in the cab, it pulls from and returns to both tanks at the same time all the time. That keeps the tanks much warmer in the cold weather.
     
    Last edited: Jan 16, 2011
  11. mizdageeragn

    mizdageeragn Medium Load Member

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    Both vent tubes are clean and open..like I said if I close the installed vent valve on the left tank it only pulls from the right tank and returns to the right tank. I'll have to try the pickup tube clean out procedure and see if that is it. Also the foam in the return line trick. I can't find an equalizer pipe or hose of any kind that runs directly from tank to tank so that can't be it. Ive tried to find some sort of equalizer valve but have had no success yet. I'm probably looking right at it and don't realize it. Will also check the caps for check ball problems. Any suggestions for finding an interior collapse on the return lines? All the lines look and feel good on the outside when I try to squeeze them.

    Thanks for all the input

    :biggrin_255:GO BEARS GO PACK:biggrin_255:
     
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