I'm trying to calibrate the fuel gauge in my 1970 Land Rover. When there's gas in the tank, it correctly reads full, but the needle goes down to empty too quickly while there's still plenty of gas in the tank. The gauge is made with a bimetallic strip connected to the needle. It takes 10v through the voltage stabilizer. The sender in the fuel tank is a variable resistor with a float. All the parts are new(ish) but from different vendors. When I tested the sender I get about 12 ohms when the float would be at its highest in the tank and 311 at the lowest. But when connected to the gauge, I get these results:
12 ohms = F (the needle can go higher than full but doesn't with this sender) and 9.8 volts at the back of the gauge
50 ohms = 3/4 tank
73 ohms = 1/2 tank
97 ohms = 1/4 tank
135 ohms = E
311 = < E (needle at the bottom) and 0 volts
(I couldn't test the voltage between 3/4 to E because I had to hold the sender in one hand to move the float.)
Does anyone have a suggestion of how to fix this? I suppose what I need to do is extend the range of resistance coming from the sender so it's from 12/Full to 311/Empty rather than 12/Full to 135/Empty. Or maybe do something to the gauge? My electrical knowledge is pretty limited so any basic suggestions would be welcome.
12 ohms = F (the needle can go higher than full but doesn't with this sender) and 9.8 volts at the back of the gauge
50 ohms = 3/4 tank
73 ohms = 1/2 tank
97 ohms = 1/4 tank
135 ohms = E
311 = < E (needle at the bottom) and 0 volts
(I couldn't test the voltage between 3/4 to E because I had to hold the sender in one hand to move the float.)
Does anyone have a suggestion of how to fix this? I suppose what I need to do is extend the range of resistance coming from the sender so it's from 12/Full to 311/Empty rather than 12/Full to 135/Empty. Or maybe do something to the gauge? My electrical knowledge is pretty limited so any basic suggestions would be welcome.