03-02-2023, 06:54 PM
Hi
The pictures show an early type G33 sender and matching gauge. The sender will be near zero ohms when full and about 30 ohms when empty.
Your new sender is 3 ohms when empty and about 150 ohms when full.
Putting a 40 ohm resistor in parallel will give you a gauge that reads backwards and will have a very non-linear scale. As the fuel level drops from full, the gauge will tend to always read nearly empty. Once you have about a gallon left, it will begin to climb fairly rapidly until it indicates 4 or 5 gallons when you are about to run out. You might find that you get used to it and it will therefore still be of use.
Even if you found a later type gauge of the opposite sense (or modified the original) you would still be stuck with the pronounced nonlinearity.
If you can find a way of refurbishing and re-using the original sender you will get a proper reading. They are pretty low-tech and are often repairable if the resistance wire is intact.
I will give some thought as to whether there is any simple discrete transistor circuit which could be used to better match your new type sender and existing gauge.
The pictures show an early type G33 sender and matching gauge. The sender will be near zero ohms when full and about 30 ohms when empty.
Your new sender is 3 ohms when empty and about 150 ohms when full.
Putting a 40 ohm resistor in parallel will give you a gauge that reads backwards and will have a very non-linear scale. As the fuel level drops from full, the gauge will tend to always read nearly empty. Once you have about a gallon left, it will begin to climb fairly rapidly until it indicates 4 or 5 gallons when you are about to run out. You might find that you get used to it and it will therefore still be of use.
Even if you found a later type gauge of the opposite sense (or modified the original) you would still be stuck with the pronounced nonlinearity.
If you can find a way of refurbishing and re-using the original sender you will get a proper reading. They are pretty low-tech and are often repairable if the resistance wire is intact.
I will give some thought as to whether there is any simple discrete transistor circuit which could be used to better match your new type sender and existing gauge.