Morris Minor Owners Club

hi ! following some meter readings of a full scale deflection on my splitty fuel gauge, it was determined that the full is obtained by a 400 ohm resistance while empty is obtained by shorting to earth.

My actual sender unit (not sure if it was ever paired to my gauge) was giving readings of much higher resistances (k homs) and therefore not working as it should. Would anyone know if the 400 ohm scale is correct? and therefore which sender unit should i be using please is it this one in the pic?

I have a sender that came with a second hand tank, but i kept the old sender when i swapped out the tanks. The petrol vapour is able to lubricate the potentiometer, and the second hand sender had been dry for many years so it makes intermittent contact. Even after a good dose of servisol the wipers aren't giving constant readings, but the float raised can read less than 200 ohms, so its not any good to you. BTW the curved metal tag you have bolted to the connector should be insulating material, and the rectangular seal should be rubber. I like your improvised float; the original is a tinned can that is soldered up.

I do wonder if there is an adjustable resistor at the gauge so that it can be trimmed for full.

ah no this is not mine copied it off esm web page to show the type! mine is exactly like yours actually!!
. Its not working properly as the resistance is too much! (into MOhms!) now its not even giving any signs of resistance!! Is there a way with contact cleaner maybe to bring it to working condition?

I'm a bit lost...

If you take the top off, the wire wound resistor that you see needs each side cleaning, so the pair of wipers can make contact. I used a nail file to scrape off the corrosion and the contact improved. The wire has an enamel coating. Once the sides are clean they are a bit shiny. The servisol didn't make much difference.

Yes thats the way around it!! the full scale resistance is around 85 Ohms