Determining fuel levels

Discussion in 'General' started by Gino230, May 21, 2019.

  1. Gino230

    Gino230 Well-Known Member

    The new (to me) FZ-07R tank is filled with tank foam (per MA rules) so for draining the fuel, the old siphon hose technique won't work. On the SV, even with the foam I could get most of it out, but not all.

    Problem is, I never know how much fuel is really in there, and short of filling the thing completely, that's no way to run a race. The old stick method won't work because of the foam issue.

    My idea is to get a set of quick disconnects and put them in the fuel line between the fuel pump and throttle bodies. After the race / session, I can open them, and use another hose to run the fuel pump and drain the tank. Then I can see how much fuel I used, and plan accordingly.

    Any problems with this method, assuming I don't blow myself up or run the battery dead forgetting the fuel pump is running?

    Club racing I just used to throw a gallon in there and call it good. MotoAmerica, we have lots of time to kill between sessions, so I have time to come up with with stuff like this.
  2. ryoung57

    ryoung57 Off his meds

    I thought that's how most race teams did it? Drain it out, then always fill a measured amount, maybe half a gallon more than you think you'd need.
  3. Gino230

    Gino230 Well-Known Member

    Right. Draining is the current problem.
  4. ryoung57

    ryoung57 Off his meds

    Yeah, but I there have been lots of threads on here over the years (most recent just a few days ago) about how to solve that issue.
  5. RM Racing

    RM Racing Tool user

    All the teams use foam. You have to create a path in the foam for a copper tube on the end of the siphon to reach the lowest point in the tank. I don’t recommend using the pump to drain the tank. They fail enough as it is. The foam also gets in the pump, so you have to check it often.
    CR750 and Gino230 like this.
  6. backbone

    backbone scarred for life

  7. dieterly

    dieterly Well-Known Member

    That’s exactly how the Honda Moto3 manual tells you how to drain the fuel tank so I say go fo for it.
    Gino230 likes this.
  8. Jon Wilkens

    Jon Wilkens Old Fart Racing

    I just made up a sleeve to put over my siphon tube to get to the bottom of the tank. I would think you could do the same and just wiggle it through all the foam to the bottom...worth a shot.
    Gino230 likes this.
  9. xTomKx

    xTomKx Well-Known Member

    What containers are you all using to measure fuel?
  10. 83BSA

    83BSA Well-Known Member

    I use a 500 ml plastic graduated cylinder for everything: oil, fuel, etc. 5 ml graduations, indestructible, easily cleaned . . . .


    xTomKx likes this.
  11. RM Racing

    RM Racing Tool user

    Google 5 liter graduated pitcher or plastic labware.
  12. Tortuga

    Tortuga Well-Known Member

    Have used both the siphon through the foam and fuel pump methods with no issues. For the fuel pump we made a harness with the oem connector on one end and alligator clips on the other and used a separate batt.
    For the jug use what people have already suggested, though make sure the graduation marks don't wipe off when exposed to petrol. Also, some pour better than others (you'll want a good one).
    We would calculate liters per lap then account for warm up, cool down , etc come race time. This also is handy in the case of a red flag to understand what's still in the tank.
  13. track wagon

    track wagon MCAS MIRAMAR

    I put gas in and go.
  14. Steve H

    Steve H Well-Known Member

    I was planning on tapping into the low pressure fuel return line. On my old TL it takes fuel back from the injectors and enters the tank very close to the fuel pump pickup.

    Just put a T in that line with manual valve which is opened to drain fuel.

    Plus use clear gasoline hose for the drain line. Put that up against the side of the tank to show exactly the level of fuel remaining.

    Can’t think why not to do this - unless maybe there is some regulation against it...

    And it’s worth getting right. People will spend significant money to save 6 or 7 pounds off the weight of their bike - then throw it all away by going out with an extra gallon of gas they don’t need.
  15. Gino230

    Gino230 Well-Known Member

    Well it's not going to be too critical for this round. 8 laps at Road America, plus a warm up lap, plus a parade lap. Probably gonna use about 2 of the 3.5 gallons.
    Steve H likes this.
  16. TWH

    TWH Well-Known Member

  17. DWhyte91

    DWhyte91 Well-Known Member

    I used to run the tank down until the fuel light came on, add say 5L of fuel, run as many laps as I could until the fuel light came on again, and that would tell me my fuel usage.
  18. BigBird

    BigBird blah

    did your fuel light still work with the foam in the tank?
  19. DWhyte91

    DWhyte91 Well-Known Member

    It did. I was worried about jamming a rod into my tank and damaging the pump or possibly breaking pieces of the foam off so this was my solution.
  20. BigBird

    BigBird blah

    mines always says low even though it could be full, and I think most have that problem.

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