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Aux Fuel Tank

Discussion in 'Stelvio Chat & Tech' started by Ray R, Dec 20, 2009.

  1. bigtex

    bigtex Cruisin' Guzzisti GT Contributor

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    Been a long winter so far, so not much riding to report. I did mock up a fairly straightforward tank that would fit between the bike and the right side pannier. First I chopped up some styrofoam and then fabbed a wooden mock-up, and it looks like a rectangular-ish tank of just over 2 gallons would tuck nicely in that space. There is probably room for a total of 3 gallons with a complex shape that extended forward, but I don't have access to plastic molding capabilities and that would be required to really fill that space. Plus, with the finally broken-in mileage of low 40's, another 2 gallons would put me safely over 200 miles, my target.

    As it is, I have a buddy that has made his own Harley tanks and I may work with him to see if we couldn't beat up and weld up some metal that would work here. I'll keep you posted.
     
  2. RokonRon

    RokonRon Tuned and Synch'ed

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    Have you got any pictures of the mock up? Kind of curious how it looks.
     
  3. Ray R

    Ray R Cruisin' Guzzisti

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    I'd also be curious as to how you'd plan to mount it, pump it, connect it in the main tank, etc.
     
  4. RokonRon

    RokonRon Tuned and Synch'ed

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    I thought you guys might be interested in something I've discovered about my Stelvio's fuel gauge since I installed my aux tank. After filling up both tanks I run off of the main tank until the top two segments on the fuel gauge go out, then I run the transfer pump for about three minutes to transfer two gallons of gas from the aux tank to the main tank.

    So here's the interesting part, the fuel gauge doesn't react to the additional fuel for several miles/minutes. The top two segments of the gauge remain off. I've tried weaving side to side and bouncing up and down on the footpegs thinking the float might be stuck, but the gauge doesn't respond. It will react on its own, but it can take several miles/minutes. Now if I stop and turn the ignition switch off and then back on again the gauge will indicate the added fuel, so I don't think it has anything do with the float.

    I don't know if all Stelvio fuel gauges work this way, but if your plan is to run a transfer pump and watch the fuel guage to determine when to shut off the pump you might want to check out how your gauge reacts first.
     
  5. WayneOrwig

    WayneOrwig GT Reference

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    Yes that should all be like that. It is in the dash programming and likely is a 'debounce' program. That way you don't have the gauge bouncing around as the float move a little.
     
  6. RokonRon

    RokonRon Tuned and Synch'ed

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    That makes sense, it would be distracting if a segment of the fuel gauge kept flashing on and off for 15 or 20 miles until it goes out for good. I just wanted to point out that the fuel gauge doesn't respond in 'real' time while adding fuel with the key on.
     
  7. Ray R

    Ray R Cruisin' Guzzisti

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    I got the call from my dealer today saying my new passenger seat has arrived. So now it's time to get serious about plumbing for this project. After Ron's trials, and looking closer at how the stock tank is plumbed, I believe the only way to tap into the stock system is to put a hole in the existing plastic tank. I looked closely at using the rubber fuel filler tube neck thingy, but there's no way I can see to tap into it for a fuel feed and still be able to put the gas cap back on. The vent lines are also out as they don't look to have a good feed into the tank, i.e., they would need pressure to open up, and they could potentially cause leaking around the cap. This means the vacume pumping method is out. So instead I'm going to use the same method Big Tex used in his thread "8 gallons, no waiting". I've purchased a 1/4" ID barbed fitting from my local hardware store (same as pictured in BT's thread). The threads are tapered so it should fit snug. Can any of you recommend a good fuel-proof sealer to use on the threads?
     
  8. RokonRon

    RokonRon Tuned and Synch'ed

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    The tapered threads should seal in the softer plastic tank without any problem, but a little teflon tape can't hurt. I put the fitting on the top of the tank so a pressure seal isn't really an issue. I did put a couple rounds of teflon on it when I was trying to pressurize the tank, but it was just screwed into the tank for quite a while with no problems.
     
  9. kwn306

    kwn306 High Miler

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    Ok, I may be way off base here and if I am someone smack me and straighten me out :lol:

    I work on the keep it simple theroy....it causes less problems.

    Tapping the plastic tank can lead to a leak, replacing the tank will cost an arm and a leg.

    Wouldn't it be easier to add a one way check valve in the present fuel line and then a brass barbed tee down stream into the stock fuel line. Then you would need to make sure the fuel pump on the aux. tank had the same psi rating as to not over pressurize the fuel injectors or install a fuel pressure regulator. You would also need to install a relay on the stock pump so that it would not be engerized while the aux fuel pump is energized.

    Fill up both tanks, run the aux first, when you feel the buck as it runs out throw the switch to power the stock fuel pump.

    Simple enough :silly:
     
  10. Ray R

    Ray R Cruisin' Guzzisti

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    Tell me again how this is simpler? ;)

    A couple of guys on this board have already tapped into their tanks with no leakage problems. And I, personally, don't feel too comfy tapping into the existing injection system with all these valves/regulators/etc.
     
  11. kwn306

    kwn306 High Miler

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    Ray,

    Fuel line leaves the tank under pressure and goes directly to the throttle bodies / fuel injectors according to the parts diagram.

    Yes I know folks on this board have tapped the tank. I probably wouldn't have a problem with that but I was one of the lucky f*ckers who's Aprilia Caponord caught fire and burned up while I was in the saddle, if it wasn't for First Gear Overpants I would have had 3rd degree burns. This was caused because of a cheap plastic fitting that Aprilia & MG uses on the bikes to disconnect the fuel line to be able to remove the tank.

    Aprilia had a recall to change to metal fitting, MG still uses the plastic units (i've changed mine), after that experience I will not screw or tap or do anything to modify a plastic fuel tank. Without a proper "bung" that has been properly hot glued in place or molded in from the manufacture is a place for a leak, the leak will hit the hot engine and then there are flames......just saying, it brought me a lot closer to the man upstairs.

    Hence, my way of what I consider safely performing the task at hand.
     
  12. RokonRon

    RokonRon Tuned and Synch'ed

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    Sounds like the problem was on the pressure side of the fuel system which makes me wonder why you want to tap into the high pressure side of the fuel injection system and add another high pressure pump, more fuel line and couplings.

    If you plumb to the top of the tank with the transfer hose fitting, there is very little if any pressure involved to cause a leak. The only fuel that hits the sealing part of the fitting would be splash up from the bottom. If the bike is on its side, I would be more worried with the gas cap leaking than the small hose fitting. But, go with what make you feel most comfortable.
     
  13. Ray R

    Ray R Cruisin' Guzzisti

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    I just got back from the dealer picking up the new passenger seat. I did some price checking, and that rubber neck fuel tank filler thingy only costs $10. So I think I'm going to explore that option a little closer. I went ahead and ordered a new one just in case. The issue I had earlier with this was trying to find a spot to tap into it. If I put any sort of fitting through it and a nut to secure it, it protrudes into the neck to the point where the fuel cap won't close. I could cut the fuel cap for clearance, but that piece costs $150, and I'm not sure what all those plastic parts on the fuel cap really do, so I want to avoid messing with it.

    Perhaps some sort of fitting that has a flared end inside the tank and a barbed fitting for the 1/4" hose outside. Stay tuned....
     
  14. kwn306

    kwn306 High Miler

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    Ron,

    Completely understand your thinking. I have a tendency to really fill a fuel tank, especailly the Stelvio because of the small tank. I have had a problem with the charcoal cansister getting filled with fuel and the bike running very poorly. I believe; and I could be wrong that filling the tank from the aux tank might become trouble some and the fuel ending up in the charcoal cansister. Someone on here attempted to do the same thing and fuel pumped out of the cap and small rubber piece / section that goes from the tank to the cap. My way might sound complicated but it is really simple to do and doesn't touch the tank. I have done this on my Kawasaki Concours, the aux tank is mounted low on the tail end of the bike and the fuel is pumped up to the carbs through a electric pump with a pressure reducer to keep from flooding the carbs.
     
  15. RokonRon

    RokonRon Tuned and Synch'ed

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    Charcoal what? I think mine fell off. :D
    I can understand that, the fuel gage doesn't react very quickly, so it would be easy to over fill the tank. I put a timer board on and run the transfer pump for three minutes (2 gallons) when the top two segments of the fuel gauge goes out, then do it again when the top two segments go out again, then run off the fuel gauge as normal.
    Hey, if it works for you, it works for me. :D Have you sourced a fuel injection pump yet? Do they make one that doesn't have to be submerged in the fuel tank or were you going to mount it inside a tank?
     
  16. kwn306

    kwn306 High Miler

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    My charcoal cansister needs to fall off as well, too damn cold right now in the pole barn to work on anything, will have to wait for the spring thaw, more snow tonight and all day tomorrow.

    There are many external units made for auto applications, I need to dig through the Stelvios shop manual to find the approx pressures and research the options.

    What I really want is for someone to design a aux tank that would fit between the right side of the bike and the right hand saddle bag, to me that is the perfect spot and it keeps the weight low.
     
  17. RokonRon

    RokonRon Tuned and Synch'ed

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    Are you concerned about running the pump dry when the aux tank goes empty and damaging the pump?
    Since I've got the aux tank on the passengers seat and mounted a GuzziTech pipe I moved my bag mounts in almost an inch and a half on each side and put a PVC storage tube on the right side, I don't have any room on that side anymore.
     
  18. kwn306

    kwn306 High Miler

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    Not really concerned about running dry, when the bike "bucks" as it's running out I will throw the switch on the handle bars to switch power back to the stock pump......and away I will go. I run my race car fuel pump dry all the time and it has been in place for 10+ years, the 5 gallon fuel cell won't make it 2 rounds at the 1/8th mile track in certain weather conditions, that's one of the reasons I keep the wife around to rescue me on the return lane at the drag strip :lol: don't tell her I said that she might not want to be my pit crew anymore :lol: :lol:
     
  19. bigtex

    bigtex Cruisin' Guzzisti GT Contributor

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    Oh? Do tell, and pics please! :?:
     
  20. RokonRon

    RokonRon Tuned and Synch'ed

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    Sorry, I'm watching my granddaughter today, so picture will have to wait until tomorrow. Here's a teaser, you can see the top of the bags in this picture I took on Wednesay while waiting for the ferry.
     

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