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 Fuel Level Sending Unit: Resistance?

 Created by: Rosebud
Orig. Posting Date User Name Edit Date
Mar 10, 2019 09:07PM Rosebud  
Mar 10, 2019 09:04PM Rosebud  
Mar 8, 2019 04:35AM RedRiley  
Mar 6, 2019 05:06PM dklawson  
Mar 6, 2019 02:06PM Rosebud Edited: Mar 6, 2019 03:54PM 
Mar 1, 2019 07:09AM dklawson  
Mar 1, 2019 04:56AM RedRiley Edited: Mar 6, 2019 03:05PM 
Mar 1, 2019 04:48AM RedRiley Edited: Mar 3, 2019 07:15AM 
Feb 28, 2019 09:39PM Rosebud Edited: Feb 28, 2019 11:21PM 
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 Posted: Mar 10, 2019 09:07PM
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Quote:
Originally Posted by dklawson

BTW, I really liked your article in Moss Motoring.
Thanks Doug. It's all relative, right?

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Mar 10, 2019 09:04PM
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Quote:
Originally Posted by RedRiley
Michael,
I was wondering how you are venting? I put a 15 gallon tank in Kreacher, and ran the vent hose down and out like the original setup, but I'm getting a lot of gas odors from the vent when the car sits in the garage. I did some reading and mostly saw recommendations that the top of the vent tube should be higher than the top of the tank. I should probably have a rollover valve too.
I'm venting to the ground, but I do have a big anti-siphon loop in the line. Maybe that's why I don't get any fuel odor. 

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Mar 8, 2019 04:35AM
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Michael,
I'm going to piggy back on your post since you mentioned the fuel cell. I was wondering how you are venting? I put a 15 gallon tank in Kreacher, and ran the vent hose down and out like the original setup, but I'm getting a lot of gas odors from the vent when the car sits in the garage. I did some reading and mostly saw recommendations that the top of the vent tube should be higher than the top of the tank. I should probably have a rollover valve too. I'm working on a solution, and I know my setup is probably different than yours with the VTEC and fuel injection. Just wondered if you had any suggestions.

 Posted: Mar 6, 2019 05:06PM
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Let us know how you resolve this.

BTW, I really liked your article in Moss Motoring.  You captured how I always felt driving either Spitfires or Midgets.

Doug L.
 Posted: Mar 6, 2019 02:06PM
 Edited:  Mar 6, 2019 03:54PM
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Quote:
Originally Posted by dklawson

Which of those parts do you currently have in your car?  Is the fuel cell currently in use?  Is the magnolia face speedo and fuel gauge currently  in use?

I'm using the Smiths speedo gauge and the fuel cell. The sending unit in my pic was just a generic—I don't remember what's installed in my cell. Spiyda and Tanksinc look promising and the resistance ranges you and Brian suggested are most helpful. Will advise. Thanks!

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Mar 1, 2019 07:09AM
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I was unable to load Brian's links directly.  If you have trouble, cut and paste the links into your browser's address bar and delete the "//" at their front so they start with "WWW".

You said your gauge is reading backwards then you included pictures of a speedometer and an aftermarket sending unit.  Which of those parts do you currently have in your car?  Is the fuel cell currently in use?  Is the magnolia face speedo and fuel gauge currently  in use?

Succinctly if you have the WIDE needle fuel gauge that does NOT respond quickly (most Minis from 1965 on) then it was designed to work with a sending unit with a NOMINAL resistance range of about 270 Ohms = Empty to 30 Ohms = Full.

As Brian said, the 240 empty to 33 full Ohm aftermarket sender should work for you.  Without touching the gauge, the 240-33 sender will work great when full.  However, the tank will become empty before the gauge indicates empty.  You will either need to identify on the gauge face where you need to fill up OR you will need to tweak the gauge calibration to match the sender.

That said, you have one more option.  Visit the Spiyda Design website (link below) and buy their Gauge Wizard board.  It will allow you match virtually any sending unit to your gauge.  The guy who runs the site and developed the boards is a Mini owner so he is aware of what is involved with our cars.
www.spiyda.com

Doug L.
 Posted: Mar 1, 2019 04:56AM
 Edited:  Mar 6, 2019 03:05PM
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 Posted: Mar 1, 2019 04:48AM
 Edited:  Mar 3, 2019 07:15AM
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 Posted: Feb 28, 2019 09:39PM
 Edited:  Feb 28, 2019 11:21PM
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Does anyone here have a good understanding of fuel level sending units? My sending unit, along with my Smiths gauge has always read backwards. When the tank is full, the gauge reads E. When the tank's empty, the gauge reads F. It's not a big deal really, I tell friends it's a British thing, E stands for "Entirely full," F is for "Fuel needed." I thought perhaps it was simply a polarity issue. After reversing the positive (+) and negative (-) leads, I realized it was a bit more complicated. I now understand sending units use resistance to send their signal to the gauge.

I was fine with the backward reading gauge, but lately the gauge has become wonky and unreliable. So, I'm going to replace the sending unit and might as well get one that reads correctly. The problem is I don't know whether I need one that uses high resistance to signal a full tank, or low resistance to indicate full. Is there anyone here that would know?

To complicate matters, I have a fuel cell with a neoprene bladder that requires a sending unit with an enclosed float (see pic). I'm sure that will limit my choices. But, let's start with the resistance issue first. Thanks!

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports