[Staowners] FUEL GAUGE

[Mal Clark]

HI everyone, continuing the problems with the fuel gauges and trying to test them on the bench,today I went to my long standing instrument man,he explained to me the workings of the gauge,basically the gauge has two internal windings, these two windings have a power wire to each,the bottom half of one of the windings has a  secondary wire,which is the wire from the sender unit, if your gauge goes to empty when it is powered up, it means both windings are recieving correct power.but if the gauge doesn't move any further it isn't recieving the signal from the sender wire,which in alot of cases the wire will be broken,and very hard to find the break,in such a small wire,a test of this circuit can be carried out with a ohm meter,one side connected to the sender pole on the gauge and the other to the earth on the gauge,if resistance is seen,then all ok,but no reading indicates an open circuit (broken wire) in my case I gave him two gauges and he managed to fix both of them. one important thing when testing your gauge on the bench,if it is out of the housing,or even still in the housing you must earth the gauge or housing,as well as your power wire and sender wire, only confusing thing with my two gauges they were negative earth,my Alpine is now negative earth,when he tested my spare gauge today he said it would not work positive earth,so I am not too sure about that, , but those of you who had tried to get your gauge going,either you haven't earthed the gauge or you have that dreaded broken wire.
  For those who have their gauge out of the dash and out of its housing,on the back you will see the two threaded posts,have the back of the gauge facing you,the right hand post is the power in, and the left post, is for the sender wire,the brass plate between the two has a soldered  wire in the middle at the top,this is the earth,when the gauge is back in its housing that brass plate earths to the housing. as I said in appears my gauges are neg earth,but I am sure if your gauge is ok it will work either the way I said, or swapping over the power and sender wire, good luck,I hope this is of some help, Mal Clark.
   
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