Low Fuel Warning Lamp???

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  • SafeAirOne
    Overdrive
    • Apr 2008
    • 3435

    Low Fuel Warning Lamp???

    Does anyone know how the low fuel warning lamp in the series III dash works? I don't think all Series IIIs have this feature but my right-hand drive, ex-6 cylinder does. It's item # 10 on this page of the RN dashboard diagram:



    This particular circuit isn't shown on the wiring schematic in the back of the RN catalog.

    The reason I ask is that I've run out of fuel twice with no indication from that light (what a joy to prime a 2.5 diesel fuel system!) The wire to the low fuel warning lamp is actually cut off on the back of the bulb socket. However, and this is the strange part, whenever I take a quick left turn followed by an immediate right, the light flashes on briefly.
    --Mark

    1973 SIII 109 RHD 2.5NA Diesel

    0-54mph in just under 11.5 minutes
    (9.7 minutes now that she's a 3-door).
  • siii8873
    Overdrive
    • Jul 2007
    • 1011

    #2
    I don't have a diagram but if it's wired like everything else, Hot lead from fuse box to the light on the dash ,from the light to the sending unit on the tank , either the sending unit is grounded or there is a ground wire to a ground from the sending unit. Probably fed from a Hot when running fuse (Green wires)
    THING 1 - 1973 88 SIII - SOLD
    THING 2 -1974 88 SIII Daily Driver - SOLD
    THING 3 - 1969 88 SIIA Bugeye Project
    THING 4 - 1971 109 SIIA ExMod - SOLD
    THING 5 - 1958 109 PU
    THING 6 - 1954 86" HT

    Comment

    • SafeAirOne
      Overdrive
      • Apr 2008
      • 3435

      #3
      Originally posted by siii8873
      I don't have a diagram but if it's wired like everything else, Hot lead from fuse box to the light on the dash ,from the light to the sending unit on the tank , either the sending unit is grounded or there is a ground wire to a ground from the sending unit. Probably fed from a Hot when running fuse (Green wires)
      That would mean that there should be 2 energized wires to the fuel level sender (one to the fuel guage and one to the low warning light) and 1 ground coming off the sender, right?

      I'm certain that my sender has one "hot" wire to the guage and one ground wire only. I'm really just trying to figure out what was originally supposed to trigger the light in a low fuel situation. I would think that the sender would complete a separate circuit, activating the light, upon reaching a preset position.

      The only other way I could imagine is by using a fuel pressure switch to trigger the light when fuel pressure drops. (the original 6-cylinder used an electric fuel pump halfway between the tank and the engine as well as an engine-driven pump). This would make it more of a "You just ran out of fuel" warning light, though.
      --Mark

      1973 SIII 109 RHD 2.5NA Diesel

      0-54mph in just under 11.5 minutes
      (9.7 minutes now that she's a 3-door).

      Comment

      • Les Parker
        RN Sales Team - Super Moderator
        • May 2006
        • 2020

        #4
        Lights -on

        The low level feature was generally only on the 2.25 Diesel and 109 V8 vehicles, as running out of fuel on these was considered a might more inconvenient.
        In either "The Green Bible" or the Haynes manual, circuit diags. are shown for both these applications.
        If you need a copy faxing let us know
        Les Parker
        Tech. Support and Parts Specialist
        Rovers North Inc.

        Comment

        • SafeAirOne
          Overdrive
          • Apr 2008
          • 3435

          #5
          Originally posted by Les Parker
          The low level feature was generally only on the 2.25 Diesel and 109 V8 vehicles, as running out of fuel on these was considered a might more inconvenient.
          In either "The Green Bible" or the Haynes manual, circuit diags. are shown for both these applications.
          If you need a copy faxing let us know
          Hmm...I should be able to track down the proper schematic, then--Thanks for steering me in the right direction. Do you know, by chance, what color this lamp is? Mine is amber. Perhaps one of the previous owners installed the lamp in that spot for some other purpose (rear fog lamp and 4-way hazzard flashers were installed at some point)

          Thanks Les
          --Mark

          1973 SIII 109 RHD 2.5NA Diesel

          0-54mph in just under 11.5 minutes
          (9.7 minutes now that she's a 3-door).

          Comment

          • jp-
            5th Gear
            • Oct 2006
            • 981

            #6
            Does the sender itself not function? In other words, does the fuel gauge work at all?

            If so, how can you run out of fuel? Do you not check the gauge?

            Just curious.

            Also, how do you prime a 2.5?
            61 II 109" Pickup (Restomod, 350 small block, TR4050)
            66 IIA 88" Station Wagon (sold)
            66 IIA 109" Pickup (Restomod, 5MGE, R380)
            67 IIA 109" NADA Wagon (sold)
            88, 2.5TD 110 RHD non-hicap pickup

            -I used to know everything there was to know about Land Rovers; then I joined the RN Bulletin Board.

            Comment

            • SafeAirOne
              Overdrive
              • Apr 2008
              • 3435

              #7
              Originally posted by jp-
              Does the sender itself not function? In other words, does the fuel gauge work at all?
              er...no. It works fine...

              Originally posted by jp-
              If so, how can you run out of fuel?
              Good question. I think it's because I'm an optimist--I only put in a little bit, hoping that diesel prices will plummet before my next fill-up. I should become a pessimist and solve this out-of-fuel problem once and for all!

              Originally posted by jp-
              Do you not check the gauge?
              Funny--that's the same thing my wife asks when she has to bring me 5 gallons of diesel!

              Originally posted by jp-
              Also, how do you prime a 2.5?
              It is a 10-step process:

              1) Put fuel in tank while regretting that you didn't get the engine shut down in time to prevent pumping air through the entire system.

              2) Loosen banjo fitting on top of fuel filter housing

              3) Reach down and actuate lever on bottom of engine-driven fuel pump until air-free diesel comes out of banjo fitting

              4) Remove your now-blackened hand and arm from the fuel pump and tighten banjo fitting

              5) Loosen bleeder on top of fuel injector distributor pump

              6) Reach down and actuate lever on bottom of engine-driven fuel pump until air-free diesel comes out of bleeder

              7) Remove your even blacker hand and arm from fuel pump and tighten bleeder

              8) Crank engine and hope for good luck

              9) Swear a bit at first (this step is optional but highly encouraged)

              10) Repeat the entire process (beginning with step 2) another 5-10 times until your fuel-pumping arm is completely black. For best results, you should increase the severity and volume of the swearing each cycle until engine starts.
              Last edited by SafeAirOne; 06-06-2008, 11:24 PM.
              --Mark

              1973 SIII 109 RHD 2.5NA Diesel

              0-54mph in just under 11.5 minutes
              (9.7 minutes now that she's a 3-door).

              Comment

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