You need to reduce the current to the gauge.

 

Would I lie to you?
You have four 220Ω resistors. Why don't you try it? What have you got to lose?

Make sure you twist all four resistors together in parallel.

I'm not at the shop. I think I might have four 220 resistors.

I know I have lots of the dual .22's.

You need to reduce the current to the gauge.

I thought the gauge was voltage sensitive rather than current sensitive. That is part of why I am having so much trouble. I still think it is voltage and not current that makes that gauge swing.

edit: I wish I was still at the shop so I could experiment...

 

Think what you may. Then why bother to come to AAC looking for advice?

You need to brush up on Ohm's Law.

In a resistive circuit, current and voltage are proportional.
Twice the voltage gives twice the current.

Half the current and you get half the voltage.

 

I accept that I am wrong. No worries, and thank you all for your help. I will give it a shot tomorrow. I will see what I can scrounge up.

My disappointment was about not being able to use those beasty little dual resistors.

 

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I thought the gauge was voltage sensitive rather than current sensitive. That is part of why I am having so much trouble. I still think it is voltage and not current that makes that gauge swing. ............

It's both.
If you apply voltage to the gauge, then there will also be current through the gauge resistance (Ohm's law).
For the gauge, you can't have one without the other.

 

Forget the 0.22Ω resistors. They're far too low a value to be useful here. Shame, but there it is.

 

I experimented with resistors on the 12V side of the gauge. With 1/3 tank of fuel, I started with 98Ω, and it read 2/3. I put in 4x 820Ω (205Ω 1W total) parallel and it reads just over 1/4, which is perfect. The resistor doesn't heat up either. Now I need to go fill the tank up and see if the gauge is very accurate. I am more concerned about running out of fuel than whether the tank shows full when it is full. I will report back, but I really didn't expect this to be such a simple fix. I was making a mountain out of a mole-hill.

How exactly does that gauge portion of the circuit work? Am I making a variable voltage divider by putting the resistors on the input because the tank sweep is a variable resistor (potentiometer)?

 

Am I making a variable voltage divider by putting the resistors on the input

The existing gauge, as per post #18, is already a potential divider, the sender unit being the variable bit. By adding those resistors you are modifying the divider action.

 

Thank you. Now I understand this completely.

I'm sorry for coming off as a jerk yesterday. I didn't realize I was, but when I went back and looked at my posts I wasn't very happy with myself. I was so pumped about making the divider out of an old receiver I couldn't get around it.

This is a really great resource for people like me who are trying to learn this stuff. Looking back on what I learned here, while it is rudimentary to you, is very new and profound to me. I didn't even know there was such a thing as a voltage divider until 2 days ago. Now I not only know it, but understand that a fuel gauge operates on that very principal.

I am reading Ohms Law. I have looked at it before, but it really never snapped for me. In case you all didn't know, I am new at electronics, and although I have done some pretty crazy stuff with it, I never had any education or training. I am just figuring this stuff out as I go.

I hope I don't blow myself up or stop my heart, but if I do, at least I will die doing what I truly enjoy. Figuring stuff out.

 

It seems like the basic problem is too much current going through the dash gauge ... to chassis ground. Just to see what happens, connect some sort of resistance ... a pot or whatever, between the dash gauge ground tab and the wire going to the chassis. With some adjustment, you should be able to get the required needle movement.

 

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