Originally Posted by Rollbar
The S-Warner gauge is for the CJ 10/73 ohm sender (new). We know the aftermarket senders are junk at best (new) and at full tank the new sender is reading 23ohms at the pink wire. When the gauge is hooked up, the gauge reads Full-this I was looking into a potentiometer to calibrate the gauge and leave it hooked up. When I fill up, dial it in and I should be good IS MY THINKING, however that goes.
Tested outside the tank was pretty close at best.
IF I read this right,
First problem is that the fuel sending unit is reading 23 ohms when the tank is full.
This could be because of several things.
1. The stop limit arms are not adjusted causing the float arm to stop before reaching full swing. You need to adjust the stops so that the float arms can travel the whole distance in the tank.
2. The float can have a crack filling with fuel causing it to float lower than it should when the tank is full.
3. The wiper arm on the sending unit was not adjusted properly and not moving the whole distance when the arm is at the end of it's travel. Surprisingly this can be adjusted.
4. The float arm is bent wrong not reaching the end of the travel when full.
Second problem is that the gauge is reading full even though the sending unit is at 23 Ohms.
First you should make sure the gauge is working. Get some 1 watt fixed ohm resistors and check out the gauge. Usually when the fuel gauge reads full when the tank is not full is because the internal regulator has stopped working usually because of a bad ground.
Say you get the fuel gauge working properly, if you put the poteniometer in parallel with the sending unit to make sure the resistance goes to 10 ohms then the gauge will be OK at ful but the rest of the range will be off.
23 Ohms + 23 Ohm in || will give 11.5 Ohms OK for full
23 Ohms + 76 Ohms in || wil give you only 17.657. So you can be running out of gas and the gauge shows 3/4 tank.
You can't put a pot in Series and hope to drop the the resistance below 23 Ohms.