I am starting a new thread for this as I think it is different enough to the other fuel gauge thread to deserve a new one. I hope that is O.K.


In my attempts to fit a fuel gauge to my LT I bought a fuel gauge from a Land Rover defender knowing it would read odd.
 I was hoping it would read backwards, i.e. full when empty and vice versa, but all it does is read full. I have tested the sender and that is good.
Apart from spending money (that I haven't got) on a BMW gauge, is there any other known gauge that would work? Or is there a way I can use the gauge I have?

Many car fuel and temperature gauges use a voltage regulator in the 12 volt supply to keep it at 12 volts. The electrical system can go up to 13.8 volts when charging. As both of these gauges use a variable earth, you would not want fluctuations in the supply voltages to result in fluctuations in the readings.
This may have something to do with your gauge or it may not.

I thought that most cars had regulators for the gauges that kept the voltage close to 5 volts.  I'll have to look in my Helm's manuals for my Ford vehicles to see.  I'll get back when I find out.

kioolt wrote:I thought that most cars had regulators for the gauges that kept the voltage close to 5 volts.  I'll have to look in my Helm's manuals for my Ford vehicles to see.  I'll get back when I find out.

I just looked it up for my 93 F150XLT.  In plain english in the shop manual "No instrument voltage regulator is used with this system."  The one I am thinking about must have been on my 78 Cougar.  I know it had an IVR because I changed it once.

I found this Youtube video that will probably help you out a lot.

https://www.youtube.com/watch?v=S7ccqSgfrRo

Thank you

The sender on the Defender 90 should be 270 (full) to 19 (empty) ohms. The BMW sender is 2 (full) to 130 (empty) ohms.  It's possible that the gauge is incompatible with the sender, even if reversed.  Is it possible for you to spring on a VDO 2-1/4" gauge that is more compatible with the sender, like a VDO 301-107 ?  BMW cars and motorcycles of 80's vintage should be using similar technology, if you are going to the breakers.


BTW, you can find  the schematic for the Additional Instruments online.

Fortunately, one of the forum members is selling loads of parts, and in those parts he has a fuel and temp gauge!!  Sorted