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Thread: Gas Gauge sending unit "float" orientation?

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    Luke Skywalker
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    Gas Gauge sending unit "float" orientation?

    I ran out of gas with the gauge showing 1/4 tank. I believe the gauge itself is OK but that I installed the sending unit in such a way as the float may be hitting the place inside where the tank shape drops off. What is the correct orientation of the float?....to the left side....to the right...or on an angle towards the back?

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    Luke Skywalker
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    Re: Gas Gauge sending unit "float" orientation?

    The obvious answer is to place the float in the lowest position but you can't see that with the tank in the car. If you're asking what the outside part looks like I can post a picture of an original sender installed in a tank but I think there are several repro senders and they are probably not all the same.
    Tom
    1960 TR3A TS73117 (under endless restoration, owned since 1964)
    1959 TR3A TS58023 (in case I never finish the one above)
    1969 Triumph Herald 13/60 (a whim)
    1970 Lotus Elan Plus 2 /0023/N
    1992 BMW325IC (fun to drive)

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    Darth Vader
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    Re: Gas Gauge sending unit "float" orientation?

    I had to do some bending of the float support wire to get it to go move from full to empty.
    I fished around through the gas filler till I had hooked the float then checked it would go through the full travel. Bent the support wire till the float did not hit the tank sides.

    I do not think the tank is empty when it reads Zero. A better situation than being empty while still showing some fuel.

    David
    TR3A TS75524L

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    Jedi Warrior 6TTR3A's Avatar
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    Re: Gas Gauge sending unit "float" orientation?

    At least it's registering something. Let's assume your baby has ventured 100,000 miles over its
    lifetime. That's about 7,000 tanks of fuel that she has gone thru. The TR3 fuel gauge itself is pretty sturdy assuming it hasn't been fooled with...but that Smiths BT3331/02 tank sending unit just can't handle that many rotations. I don't know what the factory specs were, but the six senders that I have on hand vary from 3 to 29 ohms empty and 81 to 96 ohms full. Full is no big deal, but that 26 ohm spread could leave you by the side of the road if you rely on your fuel gauge. David and Tom have the solution to make sure the float rotates free of the tank.
    What I suggest (assuming your trip meter works) is figure out just how far you can get on a full tank of fuel.
    Set your trip to zero, drive until you think your running on fumes, fill the tank, note how much you needed (14 gal. capacity +/-) and note the mileage. Reset your trip to zero each time you top off and use that mileage figure as you reference. You might also note where your fuel gauge was registering as a ball park reminder but the mileage method is better. To much trouble? Remove your sender and gauge, send it to someone who knows how to calibrate it and for $$$ you will have peace of mind !!!
    Frank


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    Re: Gas Gauge sending unit "float" orientation?

    You can also use the dipstick method as a backup to the gauge.

    Run the tank low. Dip the tank and mark your dipstick then add 10 gallons and mark the stick again. Divide the distance between the marks by 10 and you have a good idea how much gas you have in the tank.

    David
    TR3A TS75524L

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    Yoda CJD's Avatar
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    Re: Gas Gauge sending unit "float" orientation?

    Orient it so the arm is toward the center of the tank. This avoids the damper walls AND makes it easy to reach the float with a wood stick from the tank filler throat. Then you have the ability to reach in and bend the float rod to get the gage to read properly.

    I adjusted mine so when the gage rests on empty the tank has precisely one gallon remaining. With that adjustment there are two gallons unregistered on the full side. In other words, the sender doesn’t have enough travel for a perfect full to empty reading. My tank reads full until after the first two gallons burn out.
    John

    1955 TR2

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